Digital video signal recording system and reproducing apparatus

ABSTRACT

A digital video signal recording system and reproducing apparatus comprise a circuit for independently subjecting a luminance signal and two kinds of color difference signals of a color picture information to digital pulse modulation, to produce a digital luminance signal and two kinds of digital color difference signals, a circuit for dividing the digital luminance signal and the two kinds of digital color difference signals into picture element data groups, in terms of specific number of rows or columns which are adjacent on a screen, and adding a header signal at least comprising a synchronizing signal, a picture mode identification code, and a picture information quantity identification code to a beginning position of each of the divided picture element data groups comprising the digital luminance signal and the two kinds of digital color difference signals, to produce a digital video signal having a signal format in which the digital luminance, the two kinds of digital color difference signals, and the header signal are time-sequentially multiplexed, a circuit for recording the digital video signal onto a recording medium, a circuit for writing each of the divided picture element data groups picked up and reproduced from the recording medium into a memory circuit according to codes within the header signal, and a circuit for producing an analog video signal in accordance with a standard television system from picture element data read out from the memory circuit.

BACKGROUND OF THE INVENTION

The present invention generally relates to digital video signalrecording systems and reproducing apparatuses for reproducing signalsrecorded by such recording systems, and more particularly to a system inwhich picture element data groups of a component coding system areobtained by subjecting an analog video signal related to color stillpicture information corresponding to one picture or a part of onepicture or related to information corresponding to partial movingpicture to digital pulse modulation, and the picture element data groupsare divided into specific picture element data groups, to add a headersignal or discrimination signal to each of the divided picture elementdata groups and time-sequentially multiplex and record the signals ontoa rotary recording medium, and a reproducing apparatus for reproducingsignals from the rotary recording medium which is recorded according tosuch a recording system.

Recently, systems which record a digital video signal obtained bysubjecting video and audio signals to digital pulse modulation such aspulse code modulation (PCM) and a digital audio signal onto a rotaryrecording medium (hereinafter simply referred to as a disc) asvariations in geometrical configuration, and reproduce the recordedsignal as variations in the intensity of light reflected from the discor variations in electrostatic capacitance, have been developed andrealized. Further, recording systems have been proposed for digitalaudio discs, according to which a digital video signal comprising colorstill picture information is added to a digital audio signal andrecorded together on the same track on the disc. Generally, a pluralityof music programs are recorded on the same side of such a digital audiodisc, and the digital video signal comprising the color still pictureinformation is recorded in correspondence with each of the recordedmusic programs. When reproducing such a digital audio disc, the musicprograms on the disc can be reproduced by a reproducing system which iscommon throughout the world. However, the television systems are notcommon throughout the world, and there roughly exist three kinds oftelevision systems. Accordingly, in order to enable reproduction of thevideo signal recorded on the disc even if the television system employedin a region or country is different from the television system of therecorded video signal, it is first necessary to convert the recordedvideo signal into a signal format in accordance with the televisionsystem of the reproducing apparatus used in that region or countrybefore obtaining a reproduced picture. The information content of theabove digital video signal relates to a color still picture which helpsthe listener's imagination when he listens to the reproduced sounds ofthe digital audio signal. Hence, it is desirable to reproduce thedigital video signal from the disc in the signal formats which are inaccordance with each of the television systems, regardless of thedifferences in the television systems throughout the world.

The color television systems throughout the world can roughly be dividedinto three systems, that is, NTSC, PAL, and SECAM systems, according tothe transmission formats of the chrominance signal. In each of thesecolor television systems, the color video signal is constituted by aluminance signal and two kinds of color difference signals. Hence, it isdesirable to employ a component coding system which transmits the colorvideo signal by independently subjecting the luminance signal and thetwo kinds of color difference signals to digital pulse modulation, inorder to facilitate compatibility between the three systems. Moreover,it is desirable to employ the component coding system in view of thefine picture quality which may be obtained by use of a display monitorhaving input terminals for the three primary colors of red (R), green(G), and blue (B) which will probably be realized in the future, andespecially because partial moving pictures may be recorded on thedigital audio discs, and the like.

Among the digital video signals which are subjected to the componentcoding, the CCIR is presently studying standardization of the standardsespecially with respect to digital video signals which are used intelevision broadcasting studios. Regarding the (number of scanninglines)/(number of pictures per second) or the horizontal scanningfrequency, the major systems throughout the world either belong to thesystem with (525 lines)/(30 pictures) or (625 lines)/(25 pictures).Hence, a component coding system is proposed to the CCIR, in which thesampling frequency of the luminance signal is set to 13.5 MHz which is afrequency equal to six times the frequency of 2.25 MHz which is a leastcommon multiple of the horizontal scanning frequencies of the two majorsystems, the two kinds of color difference signals (R-Y) and (B-Y) arerespectively sampled at a frequency of 6.75 MHz, and the signals arerespectively quantized at a rate of 8 bits/pel. In this case, the numberof sampling points of the luminance signal on one scanning line(hereinafter simply referred to as a line), is obtained by dividing thesampling frequency of 13.5 MHz by the horizontal scanning frequency of15.625 kHz, and is equal to 864. In addition, the proposed signal formatis a format which introduces no degradation in the signal even withrespect to picture processing such as chromaky processing.

It is also desirable to transmit the digital video signal for home useaccording to the above proposed standard, however, the capacity of thepicture memory element becomes large when the number of data is large,and there will be a problem in that the transmitting time of the picturebecomes long. If the number of effective sampling points on one line is720 for the luminance signal and respectively 360 for the two kinds ofcolor difference signals (R-Y) and (B-Y) and the number of transmittinglines is 575, for example, the number of transmitted sampling pointsbecomes (720+2×360)×575=828,000. Moreover, if one sampling point isdescribed by eight bits, the number of bits of the transmitted samplingpoints becomes 828,000×8=6,624,000. This is an information quantitywhich may be stored by use of 102 64k-RAMs (random access memories)having 2¹⁶ (=65,536) bits. If such an information quantity istransmitted by use of a transmission path capable of transmittingsixteen bits at the frequency of 44.1 kHz, the required transmissiontime is equal to 6,624,000/(44,100×16)=9.39 seconds. Further, if it isassumed that the memory circuit comprises two kinds of memories, thatis, memory for write-in and memory for display, a total of 204 64k-RAMsbecome necessary. However, when transmitting the digital video signalfor home use in the digital audio disc, this will make the constructionof the memory circuit within the reproducing apparatus complex, and thecost of the reproducing apparatus will become high. Such complexity ofthe memory circuit and increased cost of the reproducing apparatus, arehighly undesirable in digital video signal reproducing apparatuses forhome use where there is a demand for low cost.

On the other hand, the present inventors have devised a digital signalrecording system in a Japanese patent application No. 56-139567.According to this devised system, one frame (or one field) of the videosignal related to the color still picture information comprises theluminance signal and the two color difference signals (B-Y) and (R-Y),and three kinds of digital video signals are obtained by independentlysubjecting the luminance signal and the two color difference signals todigital pulse modulation. The three kinds of digital video signals aresuccessively and time sequentially transmitted, and this devised systemis in accordance with the component coding system.

However, according to this devised digital signal recording system, oneframe (or one field) of the digital luminance signal is recorded, oneframe (or one field) of the first digital color difference signal isrecorded thereafter, and one frame (or one field) of the second digitalcolor difference signal is recorded after the first digital colordifference signal. Hence, if the operator attempts to change the stillpicture being displayed when reproducing a disc recorded according tosuch a recording system, the two kinds of color information willsuccessively change in terms of one picture after the luminanceinformation of the still picture of one picture changes. As a result,there was a disadvantage in that the reproduced picture was irregularand unpleasant to watch.

Accordingly, the present inventors have devised another recording systemin Japanese patent application Nos. 57-51925 through 57-51928. Whenrecording the digital video signal onto the disc according to thisdevised system, the digital luminance signal and the two kinds ofdigital color difference signals are respectively transmittedalternately in terms of information corresponding to several lines orless. Moreover, a discrimination signal or header signal for enablingthe reproducing apparatus to automatically discriminate the informationcontent of the digital video signal and the like, is recorded at thebeginning and end of the digital video signal corresponding to one frameor one field of the digital video signal transmitted with such a signalformat. However, according to this devised system, if the digital videosignal is reproduced from an intermediate point thereof due to anoperation such as random access, it becomes impossible to read out fromthe memory circuit and the display of the read-out signal thus cannot becarried out for an interval until the subsequent digital video signal isreproduced. Furthermore, there was a problem in that it was impossibleto partially modify the picture and carry out reproduction of apartially moving picture.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providea novel and useful digital video signal recording system and areproducing apparatus for reproducing signals recorded by such arecording system, in which the above described problems have beenovercome.

Another and more specific object of the present invention is to providedigital video signal recording system in which a digital luminancesignal and digital color difference signals are respectively dividedinto picture element data group where one picture element data groupcomprises a specific number of adjacent rows or a specific number ofadjacent columns in a picture, and a header signal or discriminationsignal is added to beginnings of each of the divided picture elementdata groups comprising the digital luminance signal and the two kinds ofdigital color difference signals to record a digital video signal havinga signal format in which the signals are time-sequentially multiplexedonto a rotary recording medium, and a reproducing apparatus forreproducing signals from the rotary recording medium recorded accordingto such a recording system. According to the system and apparatus of thepresent invention, even if the digital video signal is reproduced froman intermediate point thereof, the digital video signal subsequent tothe first header signal which is reproduced from the intermediate pointis written into a memory circuit within the reproducing apparatus, and apicture corresponding to the reproduced digital video signal can bedisplayed. Further, even if the transmitted word is shifted timewise dueto some cause, the error introduced because of the time shift can bereduced.

Still another object of the present invention is to provide a digitalvideo signal recording system in which the header signal recorded on therotary recording medium is constituted by at least a synchronizingsignal, a picture mode identification code, a picture informationquantity identification code, and a code for identifying a write-inaddress number in the memory circuit within the reproducing apparatus,and a reproducing apparatus for reproducing signals from the rotaryrecording medium recorded according to such a recording system.According to the present invention, even if it is discriminated from thepicture mode identification code that the digital video signal relatesto a color picture of 625 scanning lines, 525 scanning lines, a colorpicture of a number of scanning lines (1125 scanning lines, for example)providing high definition, or a moving picture in accordance with arun-length code, the format with which the digital video signal iswritten into the memory circuit can be selected to provide the mostsuitable write-in and display of the signal. In addition, according tothe discrimination of the picture information quantity identificationcode on whether the reproduced digital video signal corresponds to oneframe or one field of the video signal, the write-in with respect to thememory circuit can be carried out most suitably even if the signalformats (that is, the number of words) of the digital video signalcorresponding to one frame or the digital video signal corresponding toone field are different. Moreover, it is possible to carry outmodification of a part of the reproduced picture and display of apartially moving picture, and further, the effect due to dropout issmall.

Another object of the present invention is to provide a digital videosignal recording system in which the analog luminance signal issubjected to digital pulse modulation at a first sampling frequencywhich is exceedingly close but not over 2¹⁸, where 2¹⁸ is the productobtained by multiplying the number of picture elements of the digitalluminance signal on one scanning line and the effective number ofscanning lines in one picture of the standard television system, and thetwo kinds of analog color difference signals are independently subjectedto digital pulse modulation at a second sampling frequency which islower than the first sampling frequency, to record the picture elementdata obtained from these signals onto the rotary recording medium.According to the recording system of the present invention, a generallymarketed 64k-RAM can be efficiently used to realize the memory circuitfor storing the reproduced digital video signal provided within thereproducing apparatus which reproduces the signals from the rotaryrecording medium recorded according to this recording system, that is,the memory circuit can be realized by a least possible number of64k-RAMs. Thus, an address circuit can be provided in common withrespect to the least possible number of 64k-RAMs, and as a result, thecircuit construction of the reproducing apparatus becomes simple and thecost of the reproducing can be reduced. In addition, if the samplingfrequency of the digital luminance signal is set to 9 MHz and thesampling frequency of the two kinds of digital color difference signalsare set to 2.25 MHz, the digital video signal can be reproducedsatisfactorily by effectively using the transmission band of thegenerally marketed television receiver. Furthermore, the samplingfrequency of 9 MHz of the digital luminance signal is in a simplerelationship with the sampling frequency of 13.5 MHz used in thetelevision broadcasting studios, that is, 2:3 which is a simple ratio ofintegers exist between the two sampling frequencies. Therefore,processing such as recording and reproduction of the digital videosignal can be carried out by a digital video recorder and otherperipheral devices, and it is possible to make a master tape inaccordance with the system of the present invention by thereafterconverting the sampling frequency.

Still another object of the present invention is to provide a digitalvideo signal recording system which records a digital video signalobtained by subjecting a video signal of a standard television systemusing 625 scanning lines to digital pulse modulation. According to therecording system of the present invention, compared to a case where adigital video signal of the system using 525 scanning lines is convertedinto the digital video signal of the system using 625 scanning lines andreproduced, the vertical resolution of the reproduced picture of thesystem using 625 scanning lines is improved.

A further object of the present invention is to provide a digital videosignal recording system in which the recording is carried out by settingthe number of picture elements of the digital luminance signal on onescanning line to 456, the number of picture elements of the two kinds ofdigital color difference signals on one scanning line to a fraction of456, respectively, and the effective number of scanning lines to 572.According to the recording system of the present invention, each of thepicture element data can be efficiently stored in the 64k-RAMsconstituting the memory circuit within the reproducing apparatus, sothat the unused memory space of the 64k-RAMs is exceedingly small.Moreover, the basic construction of the memory circuit does not changeregardless of the selection of the quantization number of each of thepicture element data from any one of five to eight bits, and the pictureelement data can constantly be stored into a plurality of RAMs with highefficiency, and further, the same memory address can be supplied withrespect to all the RAMs. Thus, the write-in and read-out with respect toa frame memory can be carried out with a least number of addresscounters, and the exceedingly small unused memory space of the 64k-RAMsmay be reserved as a supplementary memory for converting the number ofscanning lines. In this case, there substantially is no unused memoryspace in the memory circuit, and the utilization efficiency of thememory is extremely high. Hence, the recording system of the presentinvention is especially suited for application in recording mediumreproducing apparatuses for home used where there is a demand for lowcost.

Another object of the present invention is to provide a digital videosignal recording system in which the header signal recorded onto therotary recording medium together with the picture element data includesa picture category or sort identification code for identifying that thepicture category is one among a plurality of picture categories ofmutually different picture information, and a reproducing apparatus forreproducing signals from the rotary recording medium recorded accordingto such a recording system. According to the present invention, it ispossible to reproduce only the picture information of a desired picturecategory from among the plurality of picture information having mutuallydifferent picture categories.

Still another object of the present invention is to provide a digitalvideo signal recording system in which a read-out specifying signal anda signal transmission termination signal are added to the digital videosignal with a timing matched with the picture display of the digitalvideo signal and recorded in continuous with the digital video signalconstituted by the picture element data groups corresponding to onepicture, so that the display is switched to the reproduced picture ofthe above digital video signal with a timing in accordance with thereproduced timing of the signal transmission termination signal, and areproducing apparatus for reproducing signals recorded according to sucha recording system. According to the present invention, it is possibleto detect the signal transmission termination signal and switch thedisplay to the reproduced picture of the digital video signal added withthe detected signal transmission termination signal from the reproducedpicture displayed up to that point in time. Moreover, in a case where arecording medium time-sequentially recorded with the component codeddigital video signal, signal transmission termination signal,synchronizing signal, and the above described codes together with thedigital audio signal is reproduced, the display of the color reproducedpicture can be switched in relation to the audio information of thereproduced digital audio signal and with a timing in accordance with thereproduced timing of the signal transmission termination signal.Accordingly, it is possible to switch the display of the color picture(especially still picture) with an extremely high accuracy at a positionsuch as a discontinuity or interruption in the reproduced sound.

A further object of the present invention is to provide a digital videosignal recording system in which the header signal recorded onto therecording medium together with the picture element data groups furtherincludes a write-in specifying code for specifying the memory circuitinto which the divided picture element data groups are to be storedbetween the two memory circuits within the reproducing apparatus, and areproducing apparatus for reproducing signals from the recording mediumrecorded according to such a recording system. According to the presentinvention, it is possible to instantaneously switch the display to thepicture obtained by the picture element data stored in thenon-displaying memory circuit from the picture obtained by the pictureelement data stored in the displaying memory circuit, and further, thedivided picture element data groups can be written into the displayingmemory circuit from which the picture element data of the picture beingdisplayed is read out and these divided picture element data groupswhich are written into the displaying memory circuit can then be readout. Hence, according to the present invention, it is possible to switcha part of the picture being displayed, and display partially movingpicture.

Another object of the present invention is to provide a digital videosignal recording system in which the header signal includes a picturetransmission identification code for identifying whether the dividedpicture element data groups are transmitted as a part of the pictureelement data groups constituting one picture, or transmitted as a partof the picture element data groups of a part of the picture, and areproducing apparatus for reproducing signals recorded according to sucha recording system. According to the present invention, even in a casewhere the synchronizing signal within the header signal is not detecteddue to dropout and the like, degradation in the picture quality of thereproduced color still picture is prevented upon transmission of thepicture in full. In addition, even if the picture transmissionidentification code cannot be detected, the divided picture element datagroups can be written according to the value of the picture transmissionidentification code detected immediately prior thereto, to minimize theeffect on the reproduced picture.

Still another object of the present invention is to provide a digitalvideo signal recording system in which picture element data of a seconddigital video signal having an information quantity corresponding toless than one picture for giving movement to the picture beingdisplayed, are written into the displaying memory circuit, and thepicture element data of a first digital video signal corresponding toone picture which are divided and reproduced by use of a transmissionperiod in which the second digital video signal does not exist, arewritten into the non-displaying memory circuit, and a reproducingapparatus for reproducing signals recorded according to such a recordingsystem. In the present invention, the non-displaying memory circuit isswitched and operated as a displaying memory circuit after the write-inof picture element data corresponding to one picture into thenon-displaying memory circuit is completed. According to the presentinvention, the display can be switched to another still picture obtainedby the first digital video signal, without interrupting the movement inthe partially moving picture obtained by the second digital videosignal.

A further object of the present invention is to provide a digital videosignal reproducing apparatus in which a header signal reproducingcircuit stops its operation to detect the synchronizing signal withrespect to an input reproduced signal during a transmission period of aspecific number of words immediately after the synchronizing signalwithin the header signal is detected. According to the reproducingapparatus of the present invention, it is possible to prevent the codesand the picture element data other than the synchronizing signal withinthe header signal from being erroneously detected as the synchronizingsignal.

Another object of the present invention is to provide a digital videosignal recording system in which the recording header signal has aconstitution such that the same contents are repeated a plurality oftimes. According to the recording system of the present invention,transmission error can be reduced even if there is dropout and the like.

Other objects and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a systematic block diagram showing an essential part of anembodiment of a digital signal recording system according to the presentinvention;

FIG. 2 shows a transmission period of a video signal of a videoinformation which is recorded by the recording system according to thepresent invention;

FIG. 3 is a systematic block diagram showing an embodiment of a headersignal generator within the block system shown in FIG.1;

FIG. 4 shows an embodiment of a signal format of a digital video signalrecorded by the recording system according to the present invention;

FIG. 5 shows an embodiment of a signal format of the header signalrecorded by the recording system according to the present invention;

FIG. 6 shows an embodiment of a signal format of one divided pictureelement data group within the digital video signal shown in FIG.4;

FIG. 7 shows an example of a signal format of the divided pictureelement data group;

FIGS. 8(A) and 8(B) respectively are diagrams showing an example of amethod of converting the number of scanning lines to 525 lines from 625lines;

FIG. 9 is a systematic block diagram showing an embodiment of anotheressential part of the recording system according to the presentinvention;

FIG. 10 shows an example of a signal format of one block of a digitalsignal recorded by the recording system according to the presentinvention;

FIG. 11 diagrammatically shows an example of a constitution of a controlsignal shown in FIG. 10;

FIG. 12 generally shows an example of a conventional recording apparatuswhich could record recording signals obtained by the recording systemaccording to the present invention;

FIG. 13 is a systematic block diagram showing an embodiment of a digitalvideo signal reproducing apparatus according to the present invention;

FIG. 14 is a diagram for explaining an example of a converting operationof a converting circuit within the block system shown in FIG. 13 forconverting the number of scanning lines;

FIG. 15 is a systematic block diagram showing an example of aconstitution of memories and the like within the block system shown inFIG. 13;

FIG. 16 is a diagram for explaining an operation in which a limitedsmall portion of the picture is changed in the reproducing apparatusaccording to the present invention;

FIGS. 17(A), 17(B), and 17(C) diagrammatically show examples ofrelationships between recording positions of signals reproduced by thereproducing apparatus according to the present invention;

FIGS. 18(A) and 18(B) respectively are diagrams for explaining thechange in display of the picture to a still picture from a partiallymoving picture in the reproducing apparatus according to the presentinvention;

FIG. 19 diagrammatically shows an embodiment of a recording sequence ofthe digital video signal reproduced by the reproducing apparatusaccording to the present invention;

FIGS. 20(A) and 20(B) respectively show examples of transmissionsequence of picture element data of the digital video signal to bereproduced by the reproducing apparatus according to the presentinvention;

FIG. 21 shows another embodiment of a signal format of the digital videosignal recorded by the recording system according to the presentinvention; and

FIG. 22 shows an embodiment of a signal format of one divided pictureelement data group within the digital video signal shown in FIG. 21.

DETAILED DESCRIPTION

First, description will be given with respect to selection of samplingfrequencies of a digital luminance signal and two kinds of colordifference signals, and selection of effective number of scanning lines.In the existing television broadcasting signal, the frequency band ofthe luminance signal is 4.2 MHz in the NTSC system, and 5 MHz or 6 MHzin the PAL system and the SECAM system. However, the frequency band ofthe luminance signal which is actually transmitted in the televisionreceiver is only up to a range of 3 MHz in the NTSC system and 3 MHz to4 MHz in the PAL system and the SECAM system. Accordingly, it ispossible to lower the sampling frequency to a range of 8 MHz, however,it is better to have some margin. Hence, the sampling frequency of theluminance signal is selected to 9 MHz which has a 2:3 relationship withthe sampling frequency of 13.5 MHz according to standard proposed at theCCIR described before. In addition, the sampling frequencies of thecolor difference signals (R-Y) and (B-Y) are respectively selected to2.25 MHz which is 1/4 the above sampling frequency of 9 MHz of theluminance signal.

The number of bits required in a memory circuit for storing a digitalvideo signal increases proportionally to the frequency band of thesignal. Accordingly, by considering a case where a digital video signalof a high definitional mode using 1125 scanning lines and 20 MHz as thefrequency band of the luminance signal which may be employed in thefuture, in addition to the digital video signal of the standard modeusing 625 or 525 scanning lines, the recording is carried out byproviding a picture mode identification code within a header signalwhich will be described hereinafter, for identifying whether the mode isthe standard mode or the high definitional mode.

The number of sampling points of the luminance signal in one scanningline of the digital video signal of the standard mode, can be obtainedby dividing the sampling frequency of 9 MHz by the horizontal scanningfrequency of 15.625 kHz, and is 576. However, horizontal blankingperiods such as the horizontal synchronizing signal interval and thecolor burst signal interval are included within these 576 samplingpoints besides the picture information, and if the sampling points ofthese horizontal blanking periods are excluded, the number of samplingpoints can be reduced to a number in the range of 456.

On the other hand, the number of bits in the generally marketed 64k-RAMis 2¹⁶ (=65,536). Hence, if four of such 64k-RAMs are used, 4×2¹⁶ =2¹⁸=262,144 bits can be obtained. If this number of bits obtained by use offour 64k-RAMs, that is, 262,144 is divided by 456 which is the effectivenumber of sampling points of the luminance signal, the quotient becomesequal to 574.87. Therefore, if the effective number of scanning lineswhich is transmitted as picture among the 625 scanning lines in oneframe, is selected to 572 which is exceedingly close to the abovequotient 574.87 but less than 574.87, each of the picture element dataof the effective sampling points of the luminance signal correspondingto one frame can be efficiently stored into four 64k-RAMs.

In addition, the information quantity of two kinds of digital colordifference signals obtained by independently subjecting the two kinds ofcolor difference signals (R-Y) and (B-Y) to digital pulse modulation atthe sampling frequency of 2.25 MHz, is 1/4 the information quantity ofthe above digital luminance signal. Thus, the picture element data ofthe effective sampling points of the two digital color differencesignals can respectively be stored efficiently into one 64k-RAM.Accordingly, if it is assumed that the quantization number of thepicture element data of one sampling point is six bits, one frame of thedigital video signal in which the digital luminance signal and the twokinds of color difference signals are time-sequentially multiplexed canbe stored into 36 64k-RAMs from an equation 6×(4+1+1)=36. Further, adigital video signal corresponding to two fields can be stored into 3664k-RAMs, which is substantially less than the case of the memorycircuit for the television broadcasting studio where 204 64k-RAMs arenecessary, and the cost can be reduced significantly.

In the case of component coding, it has been experimentally confirmedthat even if the picture element data of one sampling point is quantizedby a quantization number of six bits, the effect of quantization noiseon the picture does not introduce problems in the general reproducingapparatus for home use. Moreover, in the present embodiment of theinvention, the number of memory chips (memory circuits) required forstoring the picture element data is a least possible number, and anaddress signal generating circuit for controlling the actual storing ofthe digital video signal into the memory circuits can be used in commonwith respect to the least possible number of memory circuits. As aresult, the memory control can be carried out with ease, and it isunnecessary to provide additional buffer memory elements because of thefacilitated memory control.

Next, description will be given with respect to the recording systemaccording to the present invention. Description will first be given withrespect to an embodiment of an essential part of the recording systemaccording to the present invention, by referring to FIG.1. A videosignal source 11 such as a color television camera, flying spot scanner,video tape recorder (VTR), and the like, is supplied with a televisionsynchronizing signal from a television synchronizing signal generator 12according to the needs, and produces and supplies three primary colorsignals related to a color still picture which is to be recorded to amatrix circuit 13. The matrix circuit 13 forms a luminance signal Y andcolor difference signals (B-Y) and (R-Y) with 625 scanning lines and ahorizontal scanning frequency of 15.625 kHz, and independently suppliesthese signals to analog-to-digital (A/D) converters 14, 15, and 16. Onthe other hand, the output television synchronizing signal of thetelevision synchronizing signal generator 12 is supplied to clockgenerators 17 and 18 and memory write controllers 22 and 23.

The A/D converter 14 samples the luminance signal Y which is in therange of 5 MHz with a sampling frequency of 9 MHz for the reasondescribed before, according to a clock signal of 9 MHz obtained from theclock generator 17, and thereafter converts the luminance signal into adigital luminance signal by quantization with a quantization number ofeight bits. The digital luminance signal thus obtained from the A/Dconverter 14 is supplied to a memory 19. The A/D converter 15 samplesone color difference signal (B-Y) from among the color differencesignals (B-Y) and (R-Y) having bands which are fractions of the band ofthe luminance signal by considering the known visual characteristics ofman, with a sampling frequency of 2.25 MHz as described before,according to a clock signal of 2.25 MHz obtained from the clockgenerator 18, and thereafter converts the color difference signal into adigital color difference signal by quantization with a quantizationnumber of eight bits. This digital color difference signal is suppliedto a memory 20. Further, the A/D converter 15 similarly samples theother color difference signal (R-Y) with a sampling frequency of 2.25MHz according to a clock signal from the clock generator 18, thereafterconverts the color difference signal into a digital color differencesignal, and supplies this digital color difference signal to a memory21.

One frame of the above digital luminance signal is written into thememory 19 according to output pulses of the memory write controller 22,and read-out from the memory 19 is successively carried out according tooutput pulses of a memory read controller 24. The digital luminancesignal supplied to the memory 19 is a digital luminance signal with 456sampling points for one scanning line, that is, 456 picture elements inthe horizontal direction. If a luminance signal with 625 scanning linesand a horizontal scanning frequency of 15.625 kHz is sampled at asampling frequency of 9 MHz, the number of sampling points in onescanning line becomes 576 as described before. However, in the videosignal shown in terms of horizontal scanning periods in FIG.2, a videointerval VT actually including the video information is in the range ofapproximately 80% of one horizontal scanning period (1H). On the otherhand, the horizontal and vertical synchronizing signals and the colorburst signal may be added in the reproducing apparatus. Accordingly, thedigital luminance signal with the 456 sampling points within the videointerval VT is supplied to the memory 19. In addition, the digitalluminance signal read out from the memory 19 is a digital luminancesignal related to 572 scanning lines including the picture informationamong the 625 scanning lines for the reason described before. Moreover,for the reasons which will be explained hereinafter, it is assumed thatthe digital luminance signal is read out with a sampling frequency of88.2 kHz (or 94.5 kHz) and a quantization number of eight bits.

One frame of the digital color difference signals are written into therespective memories 20 and 21, according to a write-in control signalfrom the memory write controller 23. The data stored in the memories 20and 21 are respectively read out according to the output pulses of thememory read controller 24. The digital color difference signals suppliedto the memories 20 and 21 have a sampling frequency of 2.25 MHz which is1/4 the sampling frequency of the digital luminance signal, and aredigital signals with 114 (=456/4) sampling points in one scanning line.The digital color difference signals are read out as digital signalswith a sampling frequency of 44.1 kHz (or 47.25 kHz) and a quantizationnumber of eight bits for one picture element. In addition, the first andsecond color difference signals read out from the memories 20 and 21also relate to picture information of 572 scanning lines, similarly asin the case of the digital luminance signal.

The digital luminance signal with the sampling frequency of 88.2 kHz (or94.5 kHz) and the quantization number of eight bits which is read outfrom the memory 19, the first digital color difference signal with thesampling frequency of 44.1 kHz (or 47.25 kHz) and the quantizationnumber of eight bits for one picture element which is read out from thememory 20, and the second digital color difference signal with thesampling frequency of 44.1 kHz (or 47.25 kHz) and the quantizationnumber of eight bits for one picture element which is read out from thememory 21, are respectively supplied to a switching circuit 25.

On the other hand, signals such as a signal generated every time thestill picture signal to be recorded is changed, are applied to an inputterminal 26, and supplied to a header signal (identification signal)generator 27 which will be described hereinafter. The header signalgenerator 27 generates a header signal having a signal format shown inFIG.5, and supplies the generated header signal to a memory 28. Forexample, the memory 28 reads out the header signal with a periodcorresponding to the transmission period of 684 words, with a samplingfrequency of 44.1 kHz (or 47.25 kHz) and a quantization number ofsixteen bits, and supplies the read out header signal to the switchingcircuit 25.

The switching circuit 25 switches each of the digital signals from thememories 19, 20, 21, and 28 with a predetermined sequence, and generatesa digital video signal having a signal format shown in FIGS. 4 through6. The digital video signal generated by the switching circuit 25 issupplied to a digital recorder 29 wherein the digital video signal isrecorded onto a magnetic tape, for example. A read-out control signal isproduced from the memory read controller 24 in synchronism with a clocksignal from the digital recorder 29.

FIG. 3 shows an embodiment of the constitution of the header signalgenerator 27. In FIG. 3, ganged switches SW₁ through SW₁₆ respectivelyhave twelve contacts, and are successively switched from respectivecontacts ○1 to contacts on the right side in FIG. 3. After the gangedswitches SW₁ through SW₁₆ are respectively switched and connected torespective contacts ○12 , the ganged switches SW₁ through SW₁₆ becomeconnected to the respective contacts ○1 . A mode setting switch 30comprises sixteen contacts, and is switched according to the picturemode of the digital video signal. A 4-bit signal in accordance with theconnection state of the mode setting switch 30 is produced from anencoder 31, and supplied to respective contacts ○2 and ○8 of theswitches SW₁ through SW₄. In addition, a switch 32 is switched accordingto which channel or channels among the four transmission channels whichwill be described hereinafter, are used to transmit the digital videosignal. The switch 32 produces a transmission channel identificationcode "1P/2P" through an output terminal 43-5.

A switch 33 is switched according to whether the digital video signalcorresponds to one frame or one field. A switch 34 is switched accordingto whether the digital video signal is displayed in full on the screenor displayed on a part of the screen. Further, a switch 35 is connectedto one of four contacts according to the kind of special effect. A 2-bitsignal is produced from an encoder 36 according to the connection stateof the switch 35, and supplied to respective contacts ○2 and ○8 of theswitches SW₉ and SW₁₀. A switch 37 generates a picture category or sortidentification code "P.G", and is connected to one of four contacts.2-bit signals of difference values are produced from an encoder 38according to the connection state of the switch 37, and supplied torespective contacts ○2 and ○8 of the switches SW₁₃ and SW₁₄.

Switches 39 and 40 respectively generate a write-in specifying code"B19W" and a read-out specifying code "B19R". The output signal of theswitches 39 is supplied to respective contacts ○2 and ○8 of the switchSW₁₅, and the output signal of the switch 40 is supplied to respectivecontacts and ○2 and ○8 of the switch SW₁₆. Moreover, a clock signalapplied to an input terminal 41 is supplied to a counter 42 wherein theclock signal is counted. This counter 42 constitutes an address signalgenerator, and an output counted value of the counter 42 is supplied torespective contacts ○3 through ○6 and ○9 through ○12 of the gangedswitches SW₁ through SW₁₆.

Accordingly, when the ganged switches SW₁ through SW₁₆ are firstconnected to their respective contacts ○1 , a synchronizing signal 54ashown in FIG. 5 which will be described hereinafter indicating values"FF" and "FE" in hexadecimal by upper and lower eight bits thereof, isproduced through output terminals 43-1 through 43-16. When the gangedswitches SW₁ through SW₁₆ are then connected to their respectivecontacts ○2 , a second word 55a of the header signal which will bedescribed hereinafter, is produced in parallel through the outputterminals 43-1 through 43-16. Similarly thereafter, as the gangedswitches SW₁ through SW₁₆ are connected to their respective contacts ○3, ○4 , ○5 , . . . , and ○12 , 16-bit signals representing third, fourth,fifth, . . . , and twelfth words indicated by 56a, 57a, 58a, . . . , and59b in FIG. 5 are successively obtained in parallel through the outputterminals 43-1 through 43-16.

Next, detailed description will be given with respect to the signalformat of the digital video signal. In the digital video signal obtainedfrom the switching circuit 25, a header part of twelve words and acomponent coded digital video signal part of 684 words corresponding to2H, where H indicates one horizontal scanning period, aretime-sequentially multiplexed in an alternate manner, for example.Moreover, a signal transmission termination signal (hereinafter alsoreferred to as an end-of-data signal or EOD signal) of one word is addedto the terminal part of the digital video signal. When video informationcorresponding to one frame is to be transmitted, a digital video signalof 199,057 words as shown in FIG. 4 is recorded. Such a digital videosignal of 199,057 words comprises 286 header parts consisting of headerparts H₁ through H₂₈₆, 286 video signal parts (divided picture elementdata groups) consisting of video signal parts V₁ through V₂₈₆, and theend-of-data signal of one word indicated by EOD in FIG. 4. In FIG. 4,illustration of the header parts H₃ through H₂₈₆ and the video signalparts V₁ through V₂₈₆ are omitted. Accordingly, if one word istransmitted in sixteen bits for one channel within the signal of oneblock shown in FIG. 10 which will be described hereinafter, the digitalvideo signal corresponding to one frame is transmitted in approximately4.21 seconds when the sampling frequency is 47.25 kHz and approximately4.51 seconds when the sampling frequency is 44.1 kHz, because the periodof the signal of one block is selected to a value which is a reciprocalof the sampling frequency of the header signal.

An example of the signal format of the header part H₁ through H₂₈₆ isshown in FIG. 5. In FIG. 5, the arrangement of bits is shown along thevertical direction where an uppermost bit in FIG. 5 represents the mostsignificant bit (MSB) and a lowermost bit represents the leastsignificant bit (LSB), and the time is shown along the horizontaldirection. T indicates a unit of time corresponding to a reciprocal ofthe sampling frequency of 44.1 kHz (or 47.25 kHz) and is approximatelyequal to 22.7 μsec (or 21.2 μsec). The 16-bit data within this time unitT will hereinafter be referred to as one word. The synchronizing signal54a for indicating the beginning of the header signal is arranged at thefirst word of the header signal. The upper and lower eight bits of thesynchronizing signal 54a are respectively selected to values "FF" and"FE" in hexadecimal. Accordingly, if the synchronizing signal 54a isindicated in decimal, all the upper eight bits of the synchronizingsignal 54a become "1" while the lower eight bits of the synchronizingsignal 54a become "11111110".

The values "FF" and "FE" are only assigned to the upper and lower eightbits of the synchronizing signal 54a within the digital video signal. Ifthe video signal parts V₁ through V₂₈₆ assume such values, the values"FF" and "FE" are changed to a value "FD" in the recording system shownin FIG. 1 in advance so as to prevent the video signal parts from beingerroneously identified as a synchronizing signal. The value "FF"indicates the brightest picture data of the video signal, however, suchpicture data indicated by the value "FF" and slightly darker picturedata indicated by the value "FE" normally do not exist. Therefore, noproblems will be introduced by assigning the values "FF" and "FE" to thesynchronizing signal 54a.

Various identification codes are transmitted by the second word 55a ofthe header signal subsequent to the synchronizing signal 54a. A picturemode identification code "MODE" is arranged at the upper four bits ofthe second word 55a. This picture mode identification code indicateswhether the digital video signal to be recorded relates to a standardstill picture (description was given before in conjunction with FIG. 1by taking an example where the digital video signal to be recordedrelates to a standard still picture), a moving picture according to therun-length code, or a high definition still picture, for example. Atransmission channel identification code "1P/2P" is arranged at thefifth bit of the upper eight bits of the second word 55a. Thistransmission code identification code "1P/2P" indicates which channel orchannels among the four transmission channels which will be describedhereinafter are used to transmit the digital video signal. When thevalue of the code "1P/2P" is "1", it is identified that the transmissionmode is 1P, that is, the fourth channel is used to transmit the digitalvideo signal. In the present embodiment, description is given for thecase where the digital video signal is transmitted by use of this fourthchannel. On the other hand, when the value of the code "1P/2P" is "0",it is identified that the transmission mode is 2P, that is, the fourthchannel and the third channel are used to transmit the digital videosignal. During the transmission mode 2P in which two channels are usedto transmit the digital video signal, the digital video signaltransmitted by use of the fourth and third channels may relate tomutually different kinds of picture (scenery, portrait, playing scene,and the like, for example). In this case, the viewer may select andenjoy viewing the desired picture between the two choices. In addition,the same picture may be transmitted by use of the fourth and thirdchannels in terms of words, so that it is equivalent to a case where thesampling frequency is doubled.

Next, a picture information quantity identification code "FR/FL" isarranged at the sixth bit of the upper eight bits of the second word 55aconstituting the header signal shown in FIG. 5. This picture informationquantity identification code "FR/FL" indicates whether the digital videosignal to be transmitted corresponds to one frame or one field. It isidentified that the digital video signal corresponds to one frame whenthe value of the code "FR/FL" is "1", and corresponds to one field whenthe value of the code "FR/FL" is "0". The signal format of the videosignal part which will be described hereinafter differs according towhether the digital video signal is transmitted in terms of frames or interms of fields. Accordingly, the reproducing apparatus detects the code"FR/FL" to carry out write-in of the video signal in accordance with thesignal format used. Further, a picture transmission identification code"A/P" is arranged at the seventh bit of the upper eight bits of thesecond word 55a. When the value of the picture transmissionidentification code "A/P" is "1", it is identified that the digitalvideo signal to be transmitted relates to a still picture which shouldbe displayed in full on the screen (so-called full-picturetransmission). On the other hand, if the value of the code "A/P" is "0",it is identified that the digital video signal to be transmitted relatesto a picture which should be displayed on a part of the screen byso-called partial rewriting of the digital video signal.

Further, the value "1" indicated at the eighth bit of the upper eightbits of the second word 55a, is a value "1" in binary. If all the firstseven bits of the upper eight bits of the second word 55a become "0" andthis eighth bit also assumes the value "0", the upper eight bits of thesecond word in this case may be erroneously detected as the EOD signalshown in FIG. 4 because the upper and lower eight bits of the EOD signalare all selected to "0". For this reason, the value "1" is assigned tothe eighth bit of the upper eight bits of the second word 55a.

In addition, in FIG. 5, a 2-bit special effect code "S.E" is arranged atthe first and second bits of the lower eight bits of the second word55a. This special effect code "S.E" is provided to identify the kind ofspecial effect such as fade-in and change of picture from the top orleft of the screen applied with respect to the still picture displayed.A scanning line number converting code "6LMODE" is arranged at the twobits subsequent to the above code "S.E". A picture categoryidentification code "P.G" for identifying the category or sort ofprogram is arranged at the two bits subsequent to the scanning linenumber converting code "6LMODE".

The scanning line number converting code "6LMODE" is a code indicatingone of four kinds of mixing ratios required to convert the digital videosignal of the system using 625 scanning lines (625-line system) to thedigital video signal of the system using 525 scanning lines (525-linesystem), by converting picture information of six scanning lines topicture information of five scanning lines. That is, when carrying outsuch conversion of the number of scanning lines, the picture informationof the first through fifth scanning lines "1" through "5" of the525-line system shown in FIG. 8(B) is formed from the pictureinformation of the first through sixth scanning lines "1" through "6" ofthe 625-line system shown in FIG. 8(A). In order to form the firstscanning line (the first 1H of the first field) of the 525-line system,the picture information of the first scanning line (the first 1H of thefirst field) of the 625-line system is multiplied by 3/4 and the pictureinformation of the second scanning line (the first 1H of the secondfield) of the 625-line system is multiplied by 1/4.

As is well known, the data quantity is reduced to 1/2 (or multiplied by1/2 ) when the each bit of the digital data is shifted by one bittowards the LSB, and the data quantity is further reduced to 1/4 (ormultiplied by 1/4 ) when each bit of the digital data is further shiftedby one bit towards the LSB. The above multiplying number 3/4 is the sumof multiplying numbers 1/2 and 1/4. Accordingly, a picture informationwhich is 3/4 the picture information of the first scanning line of the625-line system can be obtained, by adding a first digital data obtainedby shifting the digital data of the first scanning line of the 625-linesystem by one bit towards the LSB and a second digital data obtained byshifting the digital data of the first scanning line of the 625-linesystem by two bits towards the LSB. Hence, it is possible to obtain thepicture information of the first scanning line of the 525-line system,by adding the picture information thus obtained which is 3/4 the pictureinformation of the first scanning line of the 625-line system, anddigital data obtained by shifting the digital data of the secondscanning line of the 625-line system by two bits towards the LSB.

Similarly, as shown in FIGS. 8(A) and 8(B), the picture information ofthe second, third, fourth, and fifth scanning lines of the 525-linesystem can be obtained by mixing the second and third scanning lines,third and fourth scanning lines, fourth and fifth scanning lines, andfifth and sixth scanning lines of the 625-line system at predeterminedmixing ratios. As shown in FIGS. 8 (A) and 8(B), four kinds of patternsare obtained for forming the picture information of the second throughfifth scanning lines of the 525-line system, and these are (1/2, 1/2),(1/2,1/2), (1/4, 3/4), and (0, 1). Hence, by specifying the mixingratios with respect to the scanning lines which are to be obtained bythe scanning line number converting code "6LMODE", it is possible toeasily carry out conversion of the digital signal to the 525-line systemfrom the 625-line system.

When the above code "6LMODE" does not exist, it is necessary to obtainthe mixing ratios by an operation such as dividing a number n (n is aninteger from 1 to 625) corresponding to the n-th scanning line of the625-line system by six and obtaining the mixing ratios from theremainder of the quotient.

When the third channel and the fourth channel are used to independentlytransmit digital video signals, the digital video signal of the normalpicture is transmitted by use of the fourth channel, for example, andthe special picture in which digital video signals of various kinds ofpictures are time-sequentially multiplexed is transmitted by use of thethird channel. In such a case, the picture category identification code"P.G" indicates the value of a category number which is assigned withrespect to each of the various categories or kinds of pictures (maximumof four categories in the present embodiment) transmitted by use of thethird channel. Each of the pictures transmitted by use of the thirdchannel must have continuity when displayed, and are pictures (musicalscores, scenery, illustrations, player, and the like, for example) whichshould not be changed to another picture before their display iscompleted. Thus, the picture category identification code "P.G"indicates the category number assigned according to the category of thepicture. Accordingly, when the viewer selects to reproduce the pictureof the third channel and specifies a desired category number, only thepicture corresponding to the specified category number is continuouslyreproduced, and the picture corresponding to that specified categorynumber is prevented from being interrupted by pictures corresponding toother category numbers.

Furthermore, in FIG. 5, 1-bit codes "B19W" and "B19R" respectively are awrite-in specifying code and a read-out specifying code with respect totwo frame memories within the reproducing apparatus which will bedescribed hereinafter. When the two codes "B19W" and "B19R" respectivelyare "0" (or "1"), the picture element data of the digital video signalis written into a first (or a second) frame memory within thereproducing apparatus, and the stored data is read out and displayed onthe screen. This means that the content of the picture is changed whiledisplaying the picture, and as a result, it is possible to display amoving picture at a part of the still picture being displayed. On theother hand, when the code "B19W" is "0" and the code "B19R" is "1", thepicture element data read out from the second frame memory is displayedwhile the picture element data is written into the first frame memory.In this case, the display on the screen is changed to the display of thepicture element data read out from the first frame memory from thedisplay of the picture element data read out from the second framememory according to the EOD signal, after the write-in with respect tothe first frame memory is completed. On the other hand, when the code"B19W" is "1" and the code "B19R" is "0", the picture element data readout from the first frame memory is displayed while the picture elementdata is written into the second frame memory.

The address signals 56a, 57a, 58a and 59a are respectively indicated byB3 through B18 in FIG. 5, and are arranged at the third through sixthwords of the header signal. These address signals 56a, 57a, 58a, and 59aindicate addresses in the memory circuit for storing the two pictureelement data corresponding to the upper and lower eight bits of each ofthe words constituting the video signal part which is transmitted incontinuous with the header signal. As described before, the televisionsignals used throughout the world either have 625 scanning lines or 525scanning lines. And, the digital video signal in the present inventionis a time-sequentially multiplexed signal of picture element data having572 scanning lines which actually include the picture information,however, the digital video signal is transmitted under the 625-linesystem. Accordingly, if reproduction is to be carried out under the525-line system, the number of scanning lines must be converted withinthe reproducing apparatus as described above before storing the pictureelement data into the memory circuit. Thus, the address signals mustspecify a total of four addresses within the memory circuit for the twopicture element data corresponding to the upper and lower eight bits ofeach of the words constituting the video signal part, with respect tothe 625-line system and the 525-line system. That is, the address signal56a indicates the address of the picture element data corresponding tothe upper eight bits of the first word constituting the video signalpart in the 625-line system, the address signal 57a indicates theaddress of the picture element data corresponding to the lower eightbits of the first word constituting the video signal part in the625-line system, the address signal 58a indicates the address of thepicture element data corresponding to the first eight bits of the525-line system obtained by the conversion of the number of scanninglines, and the address signal 59a indicates the address of the pictureelement data corresponding to the subsequent eight bits of the 525-linesystem obtained by the conversion of the number of scanning lines.

The seventh through the twelfth words of the header signal shown in FIG.5 are of a constitution similar to that of the first through sixth wordsof the header signal described heretofore. The only difference here isthat both the upper and lower eight bits of the synchronizing signal 54bcorresponding to the seventh word of the header signal, indicate thevalue "FF". The contents of the various codes in the eighth word 55b andthe address signals 56b, 57b, 58b, and 59b, are respectively selected tobe the same as the contents of the various codes in the second word 55aand the address signals 56a, 57a, 58a, and 59a. Such selection of thecontents are made for the following reasons. That is, as will bedescribed hereinafter, error correcting signals (indicated by P and Q inFIG. 10) are included within the digital video signal shown in FIG. 10which is to be recorded onto a disc 70. Most of the errors introduced atthe transmission path of the digital video signal are corrected by useof the above error correcting signals, however, there are cases whereerrors which cannot be corrected exist. In such cases, interpolationcircuit and the like is used to correct the data with respect to thedigital audio signal. With respect to the digital video signal, noproblems will be introduced by correcting the picture element data ofthe digital video signal by use of the picture element data immediatelybefore the picture element data which is to be corrected, since theadjacent picture element data are generally interrelated and close intheir values.

However, in the case of the header signal which does not haveinterrelation of data between adjacent words, it is difficult to carryout such correction. In addition, when the contents of the header signalis not transmitted, it becomes impossible to carry out write-in of thedigital video signal part immediately prior thereto. Hence, pictureelement data corresponding to 2H may become dropped, for example.Therefore, in order to avoid such inconveniences, the information of theheader part is transmitted twice as shown in FIG. 5, so that it ispossible to carry out write-in of the picture element data by use of alatter half of the header signal part even if the first half of theheader signal part is not reproduced in the transmission path. Moreover,because the values of the synchronizing signals 54a and 54b are set todifferent values, it is possible to discriminate whether thesynchronizing signal is the synchronizing signal 54a of the first halfof the header signal part or the synchronizing signal 54b of the latterhalf of the header signal part. It is of course possible to transmit theheader signal only once, in which case the header signal will beconstituted by six words.

Next, description will be given with respect to the signal format of thevideo signal parts (divided picture element data groups) V₁ through V₂₈₆shown in FIG. 4. FIG. 6 shows an embodiment of the signal format of thevideo signal part V₁. In FIG. 6, the bit arrangement is shown along thevertical direction with the uppermost bit indicating the MSB and thelowermost bit indicating the LSB, and the time is shown along thehorizontal direction, as in FIGS. 4 and 5. In the present embodiment,each of the 286 video signals parts V₁ through V₂₈₆ are respectivelyconstituted by 684 words as described before, and each of the videosignal parts are transmitted with the picture element data of onescanning line between adjacent scanning lines arranged at the uppereight bits and the picture element data of the other scanning linearranged at the lower eight bits. Accordingly, the signal format of thefirst video signal part V₁ becomes as shown in FIG. 6 wherein a digitalvideo signal series of each of the sampling points in the first scanningline (the first 1H of the first field) positioned at the uppermost partof the picture, is arranged at the upper eight bits of each of the wordsconstituting the video signal part V₁. That is, among the plurality ofpicture elements arranged in a matrix form and constituting one picture,the picture element data from the first row of picture element groupsare arranged at the upper eight bits of each of the words constitutingthe video signal part V₁. On the other hand, a digital video signalseries of each of the sampling points in the second scanning line (thefirst 1H of the second field) positioned next to the uppermost part ofthe picture, is arranged at the lower eight bits of each of the wordsconstituting the video signal part V₁. That is, among the plurality ofpicture elements arranged in the matrix form and constituting onepicture, the picture element data from the second row of picture elementdata groups are arranged at the lower eight bits of each of the wordsconstituting the video signal part V₁.

Further, in FIG. 6, Y₀ through Y₄₅₅ (Y₁₀ through Y₄₅₅ are not shown)indicate positions of each of the picture element data from the firstsampling point to the 456-th sampling point of the digital luminancesignal in the first scanning line, and Y₄₅₆ through Y₉₁₁ (Y₄₆₆ throughY₉₁₁ are not shown) indicate positions of each of the picture elementdata from the first sampling point to the 456-th sampling point of thedigital luminance signal in the second scanning line. In addition,(R-Y)₀ through (R-Y)₁₁₃ and (B-Y)₀ through (B-Y)₁₁₃ ((R-Y)₂ through(R-Y)₁₁₃ and (B-Y)₂ through (B-Y)₁₁₂ are not shown) respectivelyindicate positions of each of the picture element data from the firstsampling point to the 114-th sampling point of the digital colordifference signals (R-Y) and (B-Y) in the first scanning line. (R-Y)₁₁₄through (R-Y)₂₂₇ and (B-Y)₁₁₄ through (B-Y)₂₂₇ ((R-Y)₁₁₆ through(R-Y)₂₂₇ and (B-Y)₁₁₆ through (B-Y)₂₂₆ are not shown) respectivelyindicate positions of each of the picture element data from the firstsampling point to the 114-th sampling point of the digital colordifference signals (R-Y) and (B-Y) in the second scanning line. Hence,the video signal part V₁ comprises picture element data groupscorresponding to 2H of the first and second scanning lines. The signalformat of the video signal part V₁ is such that the picture element dataof the four sampling points of the digital luminance signal and thepicture element data of one respective sampling point of the two kindsof digital color difference signals, that is, a total of six pictureelement data are considered as one unit, and the the digital videosignal data are transmitted in terms of this unit. The video signalparts V₂ through V₂₈₆ have the signal formats similar to that of thevideo signal part V₁. The picture element data of the same scanning lineare not arranged in the same word as shown in FIG. 7, but the pictureelement data of two adjacent scanning lines are divided and arranged inthe same word as shown in FIG. 6. This arrangement shown in FIG. 6 isemployed, so that the number of scanning lines can be converted withease to enable conversion of the system of the digital video signal tothe 525-line system from the 625-line system. Furthermore, when thepicture element data of two adjacent scanning lines are divided andarranged in the same word and transmitted simultaneously, the number ofoperations involved in carrying out write-in and read-out with respectto the memory during the operation in which the system is converted intothe 525-line system from the 625-line system can be reduced. All thesixteen bits of the EOD signal are "0", however, when the all the bitsof the word constituting the video signal parts V₁ through V₂₈₆ assumethe value "0", the value of the word is changed to a close value so thatthe LSB of that word is "1" and the rest of the bits are all "0" inorder to prevent that word from being erroneously detected as the EODsignal.

Among the different picture information of various categories (maximumof four categories in the present embodiment) identified by the picturecategory identification code "P.G", the same picture information may betransmitted by the video signal parts V₁ through V₂₈₆ corresponding toone frame or transmitted as a whole by the video signal partcorresponding to one field. However, the transmission method of thepicture information is not limited to these methods, and for example,picture information of mutually different categories may coexist and betransmitted successively. In this case where the picture information ofmutually different categories coexist and are transmitted successively,it is possible to select and display the picture information of one ofthe mutually different categories within the same reproducing intervalof the digital audio signal which will be described hereinafter. Thepicture information of the different categories are transmittedtime-sequentially, and the time required to transmit 684 words of onevideo signal part is actually different according to the video signalpart, however, no matter which picture information is displayed, thedifference in the displaying time of the picture information of themutually different categories cannot be sensed by the human eye. Amongthe picture information of the mutually different categories, thetransmission quantity per unit time with respect to one pictureinformation may be made larger than other picture information.

Next, description will be given with respect to a recording system fortime-sequentially recording the digital video signal having the signalformat shown in FIGS. 4 through 6 onto the disc together with thedigital audio signal. In the recording system according to the presentinvention, the digital video signal is transmitted by the transmissionpath of one or two channels among the four channels, and the digitalaudio signal is transmitted by the transmission path of the remainingthree or two channels. However, description will hereinafter be givenwith respect to a case where the digital video signal is transmitted byone channel and the digital audio signal is transmitted by the remainingthree channels.

FIG. 9 is a systematic block diagram showing an embodiment of anessential part of the system according to the present invention. In FIG.9, those parts which are the same as those corresponding parts in FIG. 1are designated by the same reference numerals. Three channels of analogaudio signals are respectively applied to input terminals 60, 61, and62, and supplied to an analog-to-digital (A/D) converter 65. A signalfor central acoustic image intersect is included in the three channelsof analog audio signals, and by this signal, it is possible to obtainthe real image of the central sound source and enlargement of thelistening range which could not be obtained in the conventional2-channel stereo. In addition, a start signal is applied to an inputterminal 63, and a cue signal is applied to an input terminal 64. Thecue signal is generated every time the music program of the 3-channelanalog audio signal changes to a difference music program. The startsignal and the cue signal are supplied to a control signal generatingcircuit 66.

It will be assumed that a digital signal with a sampling frequency of44.1 kHz (or 47.25 kHz) and a quantization number of sixteen bits andhaving an information quantity of one channel, is recorded timesequentially onto the disc 70 which will be described hereinafter forfour channels on one track turn. Thus, in this case, the 3-channelanalog audio signal supplied to the A/D converter 65 is sampled at asampling frequency of 44.1 kHz (or 47.25 kHz) with respect to each ofthe channels, and the signal thus converted into a digital audio signal(PCM audio signal) with a quantization number of sixteen bits withrespect to one picture is supplied to a signal processing circuit 67. Atthe same time, the digital video signal having the signal format shownin FIG. 4 with the sampling frequency of 44.1 kHz (or 47.25 kHz) and thequantization number of sixteen bits with respect to one picture, whichis reproduced by the digital recorder 29, is also supplied to the signalprocessing circuit 67. Moreover, the control signal generating circuit66 which is supplied with the start signal through the input terminal 63and the cue signal through the input terminal 64, generates a controlsignal having a constitution which will be described hereinafter inconjunction with FIG. 11, and supplies this generated control signal tothe signal processing circuit 67. As will be described hereinafter, thecontrol signal is used for controlling the position of the pickup andreproducing element during an operation such as a random access and thelike.

With respect to the 16-bit input digital signals and the control signalof a total of four channels, the signal processing circuit 67 rearrangesthese parallel data into series data, and further sections the digitalsignals of each of the channels into predetermined sections and subjectsthese digital signals to time-division multiplexing by interleaving. Therecording signal is formed by further adding an error code correctionsignal, error code detection signal, and synchronizing bit forindicating the beginning of the block (frame) to the time-divisionmultiplexed signal.

FIG. 10 diagrammatically shows an example of one block (one frame)within the recording signal thus formed by the signal processing circuit67. One block is constituted by 130 bits, and the repetition frequencyis 44.1 kHz (or 47.25 kHz) which is equal to the sampling frequency. InFIG. 10, a 10-bit synchronizing signal bit having a fixed pattern forindicating the begging of the block is indicated by SYNC, 16-bit digitalaudio signals of a total of three channels are respectively indicated byCh-1 through Ch-3, and 16-bit digital video signal reproduced from thedigital recorder 29 is indicated by Ch-4. In addition, P and Q indicatedin FIG. 10 respectively are 16-bit error code correction signals, andare signals which are formed satisfying the following equations, forexample.

    P=W.sub.1 ⊕W.sub.2 ⊕W.sub.3 ⊕W.sub.4           (1)

    Q=T.sup.4 ·W.sub.1 ⊕T.sup.3 ·W.sub.2 ⊕T.sup.2 ·W.sub.3 ⊕T·W.sub.4                 (2)

In the above equations (1) and (2), W₁, W₂, W₃, and W₄ respectivelyindicate each of the 16-bit digital signals Ch-1 through Ch-4 (normally,these signals are digital signals in different blocks), T indicates acompanion matrix of a predetermined polynomial, and ⊕ indicates amodulo-2 addition in terms of each of the corresponding bits.

In FIG. 10, a 23-bit error code detection signal is indicated by CRC.The error code detection signal CRC is a 23-bit remainder when each ofthe words Ch-1 through Ch-4, P, and Q are divided by a formationpolynomial X²³ +X⁵ +X⁴ +X+1, for example. Upon reproduction, the signalsfrom the 11-th bit to the 129-th bit of the same block are divided bythe above formation polynomial, and this error code detection code isused to detect that there is no error when the remainder is zero. Thecontrol signal described previously is indicated by Adr. One bit of thiscontrol signal Adr is transmitted within one block, and for example, allthe bits of the control signal are transmitted by 126 blocks.Accordingly, the control signal shown in FIG. 11 is constituted from 126bits. Thus, if the rotational speed of the disc 70 is 900 rpm, 3150blocks are recorded or reproduced for one track turn of the disc 70, andas a result, the above 126-bit control signal is recorded or reproduced25 times for one track turn of the disc 70.

FIG. 11 diagrammatically shows an example of the constitution of theabove described control signal. The 126-bit control signal isconstituted from a 42-bit first chapter code CP-1, 42-bit second chaptercode CP-2, and 42-bit time code TC. The first chapter code CP-1comprises a 17-bit synchronizing signal, 4-bit mode signal, 8-bitchapter signal, 12-bit chapter local address, and 1-bit parity codewhich is obtained by carrying out a modulo-2 addition with respect tothe signal bits of the mode signal through the chapter local address.The second chapter code CP-2 has the same constitution and values as thefirst chapter code CP-1, except for the value of the synchronizingsignal. The mode signal is a signal indicating the kind of the fourchannels of digital signal recorded on the disc 70. For example, if themode signal is "1100", three channels of digital audio signals and onechannel of digital video signal are recorded. Similarly, four channelsof digital audio signals are recorded when the mode signal is "1101",two channels of two kinds of digital audio signals are recorded when themode signal is "1110", and two channels of digital audio signals and twochannels of digital video signals are recorded when the mode signal is"1111".

Further, the above chapter signal is a signal indicating the position ofa recorded music program from the point on the disc 70 where therecording of the signal is started.

For example, the time code TC shown in FIG. 11 comprises a 17-bitsynchronizing bit, 4-bit mode signal for indicating the kind of the fourchannels of digital signals recorded on the disc 70 similar to the modesignals within the first and second chapter codes CP-1 and CP-2, 16-bittime identification code for indicating the position of the recordedmusic program on the disc 70 in terms of time from the point where therecording of the signal is started, 4-bit track number code which isincremented by one for every track turn of the disc 70 and assumes avalue from zero to fourteen in binary code, and 1-bit parity code. Thetime identification code is indicated by a value such as minutes andseconds, and the minimum unit is one second. However, when the disc 70rotates at a rotational speed of 900 rpm, the disc 70 undergoes 15revolutions per second. Hence, even if the time identification codeassumes the same value, it is possible to identify the position of therecorded music program by the track number code for each revolution ofthe disc 70.

The digital signal shown in FIG. 10 comprising 130 bits in one block issuccessively obtained in series in terms of blocks from the signalprocessing circuit 67, and supplied to a modulation circuit 68 providedin a succeeding stage. The signal supplied to the modulation circuit 68is subject to modified frequency modulation (MFM), for example, and isconverted into a frequency modulating signal by frequency-modulating acarrier of 7 MHz, for example. This frequency modulating signal from themodulation circuit 68 is recorded onto the disc 70 by a recordingapparatus 69 using laser beam and the like.

A conventional recording apparatus shown in FIG. 12 such as that shownin a U.S. Pat. No. 4,315,283, for example, may be used as the recordingapparatus 69. In FIG. 12, a laser light emitted from a laser lightsource 81 is eliminated of its drift, noise, and the like at a lightmodulator 82, and is reflected at a reflecting mirror 83 and dividedinto two optical paths by a half mirror 84. One of the divided laserlight is modulated by the output frequency modulating signal of theabove modulation circuit 68 and the third tracking control signal fp3which are obtained through an input terminal 86 at a light modulator 85,and converted into a first modulated light beam. The other divided laserlight is modulated by the first tracking control signal fp1 or thesecond tracking control signal fp2 alternately obtained from a recordingoriginal disc 70a through an input terminal 88 at a light modulator 87,and is converted into a second modulated light beam.

The first modulated light beam is reflected at a reflecting mirror 89and changed of its optical path, and is passed through an informationrecording optical system comprising a cylindrical lenses 90 and 91, aslit 92, and a convex lens 93, and then formed into a rectangular lightbeam on the recording original disc 70a. On the other hand, the secondmodulated light beam is passed through a tracking recording opticalsystem comprising a convex lens 94, a slit 95, and a convex lens 96, andformed into a circular light beam on the recording original disc 70a,and further changed of its optical path by a reflecting mirror 97. Thefirst and second modulated light beams thus formed into light beams ofpredetermined shapes, are composed on substantially the same opticalaxis by a deflection prism 98, and then pass through a half mirror 99.The optical paths of the light beams obtained through the half mirror 99are changed by a prism 100, and the light beams then pass through a slit101 and a recording lens 102 to reach the recording original disc 70a. Alayer 104 of photosensitive agent is formed on a glass substrate 103 ofthe recording original disc 70a, and as a result, the first modulatedlight beam is focused as a rectangular spot 105 while the secondmodulated light beam is focused as a circular spot 106 on the recordingoriginal disc 70a.

The recording original disc 70a is a disc-shaped medium, and is rotatedat a predetermined rotational speed. In addition, the light reflected bythe half mirror 99 is applied to a signal monitoring system 107, whilethe light reflected by the prism 100 is applied to a monitoring opticalsystem 108. The distance between the two modulated light beams on therecording original disc 70a is measured by the monitoring optical system108, and the error in the distance between the two modulated light beamsis monitored by the signal monitoring system 107. This error in thedistance between the two modulated light beams on the recording originaldisc 70a, is corrected by moving the cylindrical lens 90 upwards anddownwards in FIG. 12.

The recording original disc 70a is subjected to the known developingprocesses and disc manufacturing processes, to form a stamper disc. Thedisc 70 which is duplicated by the stamper disc, is recorded with afrequency-modulated signal of the signal which is obtained bysuccessively time-sequentially multiplexing the three channels ofdigital audio signals and the one channel of digital video signal havingthe signal format shown in FIGS. 4 or 6 in terms of blocks where oneblock has the signal format shown in FIG. 10. This frequency-modulatedsignal is recorded on a spiral main track on the disc 70 as rows ofintermittent pits. The first and second tracking control signals fp1 andfp2 of a constant frequency within a band lower than the band of theabove frequency-modulated signal, are alternately recorded as rows ofintermittent pits on subtracks at substantially intermediate partsbetween centerlines of mutually adjacent main tracks for each track turnof the disc. Further, the third tracking control signal fp3 is recordedon the main track at parts where the sides on which the first and secondtracking control signals fp1 and fp2 are recorded change over. Trackinggrooves for guiding the reproducing stylus are not formed on the disc70, and the disc 70 has an electrode function.

Hence, according to the present embodiment, the component coded digitalvideo signal part which is a time-sequentially multiplexed signal of thepicture element data from each of the picture elements arranged in thematrix form on the screen, is divided into picture element data ofpicture element groups of the two adjacent rows. The header signalhaving the signal format shown in FIG. 5 is then added to each of thedivided signals, and the EOD signal is added to one word at the lastpart of the signal. The digital video signal having such constitution istime-sequentially multiplexed with the digital audio signal, andsuccessively recorded onto the disc 70.

Next, description will be given with respect to an embodiment of areproducing apparatus according to the present invention for reproducingthe digital signal recorded on the above described disc 70, by referringto FIG. 13. The disc 70 is placed onto a turntable (not shown) androtated at a rotational speed of 900 rpm. A bottom of a reproducingstylus 110 slides over the surface of the rotating disc 70. Thereproducing stylus 110 is fixed to one end of a cantilever 111, and apermanent magnet 112 is fixed to the other base end of the cantilever111. The part of the cantilever 111 where the permanent magnet 112 isfixed, is encircled by a tracking coil 113 and a jitter compensationcoil 114 fixed to the reproducing apparatus. Right and left coil partsof the jitter compensation coil 114 are wound in the same phase, andthus, attracting forces or repulsive forces simultaneously act on thepermanent magnet 112 according to the polarity of a jitter compensationsignal. Hence, the cantilever 111 is moved along a tangential directionwith respect to the tracks on the disc 70, to compensate for the jitterintroduced due to the surface oscillation or eccentricity of the disc70. Further, the tracking coil 113 generates a magnetic field along adirection perpendicular with respect to the magnetic direction of thepermanent magnet 112. Accordingly, the cantilever 111 is moved along oneof the directions in the width direction of the track according to thepolarity of a tracking error signal from a tracking servo circuit 115with a displacing quantity according to the magnitude of the trackingerror signal.

A high-frequency reproduced signal is obtained from a pickup circuit116. This pickup circuit 116 comprises a resonance circuit which isvaried of its resonance frequency in response to the variations inelectrostatic capacitance formed between an electrode fixed to a rearsurface of the reproducing stylus 110 by deposition and the disc 70according to the rows of intermittent pits, a circuit for applying asignal of a constant frequency to this resonance circuit, a circuit foramplitude-detecting a high-frequency signal from the resonance circuitvarying in its amplitude according to the above variations in theelectrostatic capacitance, and a circuit for preamplifying theamplitude-detected high-frequency signal (reproduced signal). Thehigh-frequency signal obtained from the pickup circuit 116 is suppliedto a frequency demodulating circuit 117 wherein the main informationsignal (the digital audio signals and the time-sequentially multiplexeddigital video signal in this case) from the main track is demodulated onone hand, and a part thereof is separated and supplied to the trackingservo circuit 115.

The tracking servo circuit 115 frequency-selects and obtains the firstthrough third tracking control signals fp1 through fp3 from thereproduced signal. Envelopes of the first and second tracking controlsignals fp1 and fp2 thus obtained are detected and passed through adifferential amplifier (not shown) to obtain the tracking error signal,and this tracking error signal is supplied to the tracking coil 113.Here, it must be noted that the positional relationships between thefirst and second tracking control signals fp1 and fp2 with respect tothe main track changes for each track turn of the disc 70. Accordingly,the tracking polarity is reversed for each track turn of the disc 70, bya switching pulse produced according to the detection or reproduction ofthe third tracking control signal fp3. The tracking servo circuit 115drives the tracking coil 113 so that the reproducing stylus 110 isforcibly shifted by one or more than track pitch along the track widthdirection according to a kick instruction signal, when the kickinstruction signal is applied to an input terminal 118.

On the other hand, the demodulated digital signal obtained from thefrequency demodulator 117 is applied to a decoder 119 wherein thedemodulated digital signal is subjected to MFM demodulation and formedinto the time-sequentially multiplexed signal having the signal formatshown in FIG. 10. The beginning of the block of the time-sequentiallymultiplexed signal is detected according to the synchronizing signal bitSYNC, and the series signal is converted into a parallel signal, andfurthermore, the error is detected. The error code correction signals Pand Q are used to correct the error and restore the signal only when anerror is detected. Hence, by correcting the error and restoring thesignal according to the needs, three channels of the 16-bit digitalaudio signals comprising no errors among the four channels of 16-bitdigital signals restored to their original order with interleavingsignal arrangement, are converted into analog audio signals by adigital-to-analog (D/A) converter within the decoder 119 and producedthrough output terminals 120a, 120b, and 120c. In addition, the pickupcontrol signal is supplied to a predetermined circuit (not shown) forcarrying out high-speed search and the like.

The digital video signal having the signal format shown in FIG. 4 (orFIG. 6) which is time-sequentially reproduced from the fourth channel,is supplied to a converting circuit 121 shown in FIG. 13 for convertingthe number of scanning lines. The number of scanning lines is convertedinto 525 lines from 625 lines at the converting circuit 121.

FIG. 14 diagrammatically shows the manner in which the number ofscanning lines is converted. In FIG. 14, Y₀ indicates the pictureelement data of the first sampling point of the digital luminance signalin the first scanning line of the 625-line system, and Y₄₅₆ indicatesthe picture element data of the first sampling point of the digitalluminance signal in the second scanning line of the 625-line system, asin the case shown in FIG. 6. As seen from the case shown in FIG. 6, theabove picture data Y₀ and Y₄₅₆ are transmitted first in the video signalpart V₁. A data obtained by multiplying 3/4 to the picture element dataY₀, is formed by adding the data obtained by shifting the data Y₀ by onebit towards the LSB and the data obtained by shifting the data Y₀ by twobits towards the LSB. A data obtained by multiplying 1/4 to the pictureelement data Y₄₅₆, is formed by shifting the data Y₄₅₆ by two bitstowards the LSB. A picture element data Y₀ indicating the pictureelement data of the first sampling point of the digital luminance signalof the 525-line system in the first scanning line, is obtained by mixingthe above data obtained by multiplying 3/4 to the data Y₀ and the dataobtained by multiplying 1/4 to the data Y₄₅₆. Moreover, a data obtainedby multiplying 1/2 to the picture element data Y₄₅₆ is stored into asupplementary memory (1-line memory) 140. Thereafter, the data obtainedby multiplying 3/4 to the picture element data of each of the samplingpoints in the first scanning line of the 625-line system, and the dataobtained by multiplying 1/4 to the picture element data of each of thesampling points inthe second scanning line of the 625-line system, aresimilarly mixed with respect to the sampling points in the same word, toobtain the picture element data of the first scanning line of the525-line system.

The picture element data of each of the sampling points in the thirdscanning line of the 625-line system related to the video signal part V₂which is next reproduced is multiplied by 1/2, by shifting the data byone bit towards the LSB, and mixed with the picture element data readout from the supplementary memory 140 with respect to the same samplingpoint. As a result, the picture element data of the second scanning lineof the 525-line system is obtained. In FIG. 14, Y₉₁₂ indicates thepicture element data of the first sampling point of the digitalluminance signal in the third scanning line of the 625-line system, andY₄₅₆ indicates the picture element data of the first sampling point ofthe digital luminance signal in the second scanning line of the 525-linesystem. Further, Y₁₃₆₈, Y₁₈₂₄, and Y₂₂₈₀ respectively indicate pictureelement data of the digital luminance signal of the 625-line system.Y₁₃₆₈ indicates the picture element data of the first sampling point inthe fourth scanning line, Y₁₈₂₄ indicates the picture element data ofthe first sampling point in the fifth scanning line, and Y₂₂₈₀ indicatesthe picture element data of the first sampling point in the sixthscanning line. In addition, Y₉₁₂, Y₁₃₆₈, and Y₁₈₂₄ respectively indicatepicture element data of the digital luminance signal of the 525-linesystem. Y₄₁₂ indicates the picture element data of the first samplingpoint in the third scanning line, Y₁₃₆₈ indicates the picture elementdata of the first sampling point in the fourth scanning line, and Y₁₈₂₄indicates the picture element data of the first sampling point in thefifth scanning line.

As seen from FIG. 14, the data obtained by multiplying 1/2 to thepicture element data such as Y₉₁₂ of each of the sampling points in thethird scanning line of the 625-line system, and the data obtained bymultiplying 1/2 to the picture element data such as Y₁₃₆₈ of each of thesampling points in the fourth scanning line of the 625-line system, aremixed to obtain the picture element data such as Y₉₁₂ of each of thesampling points in the third scanning line of the 525-line system.Moreover, the data obtained by multiplying 1/2 to the picture elementdata such as Y₁₃₆₈ of each of the sampling points in the fourth scanningline of the 625-line system, is stored into a supplementary memory(1-line memory) 141. Similarly, the picture element data such as Y₁₈₂₄of each of the sampling points in the fifth scanning line of the625-line system is multiplied by 3/4, and mixed with the data obtainedby multiplying 1/2 to the picture element data with respect to the samesampling point read out from the supplementary memory 141, to obtain thepicture element data such as Y₁₃₆₈ of the fourth scanning line of the525-line system. Furthermore, the picture element data such as Y₂₂₈₀ ofthe sixth scanning line of the 625-line system is used as it is as thepicture element data such as Y₁₈₂₄ of the fifth scanning line of the525-line system. Operations similar to the above described operationsare repeatedly carried out. Therefore, the picture element data of thesix scanning lines of the 625-line system are mixed with predeterminedmixing ratios, and converted into picture element data of the fivescanning lines of the 525-line system.

As may be understood from the description given heretofore, thesupplementary memories 140 and 141 used for carrying out operations whenconverting the number of scanning lines, may be realized by a common1-line memory. In this case, the common 1-line memory is used in turnsas the supplementary memories 140 and 141. On the other hand, the numberof sampling points (the number of picture element data) of the digitalluminance signal can be described by the product of the number ofsampling points in one horizontal scanning line which is 456 and theeffective number of scanning lines which is 572, and is equal to260,832. The number of bits available by use of four 64k-RAMs is 262,144(=2¹⁶ ×4), and therefore, 1312 bits are additionally available. That is,sufficient memory space or capacity is additionally available forstoring the picture element data of sampling points of the digitalluminance signal corresponding to over 2H, when four 64k-RAMs are used.Accordingly, this additionally available memory space can be used as thesupplementary memories 140 and 141. The read-out and write-in withrespect to the supplementary memories 140 and 141 are carried out withina horizontal blanking period of a color video signal of a standardtelevision system (NTSC system in the present embodiment) which isobtained through an output terminal 136.

The scanning line number converting circuit 121 converts the pictureelement data of the 625-line system into picture element data of the525-line system in the manner described heretofore, and the convertingoperation is simple because the picture element data are transmittedwith the signal format shown in FIG. 6. This scanning line numberconverting circuit 121 is only needed in the reproducing apparatus shownin FIG. 13 where it is necessary to reproduce and produce an analogcolor video signal in accordance with the NTSC system which is a525-line system, and there is no need for the scanning line numberconverting circuit 121 in reproducing apparatuses where it is onlynecessary to reproduce and produce an analog color video signal inaccordance with the PAL system or the SECAM system which are 625-linesystems. However, a switch for switching the input and output of thescanning line number converting circuit 121 may be provided in somereproducing apparatuses. In such reproducing apparatuses, the switch canbe switched to make the scanning line number converting circuit 121operative or inoperative according to the number of scanning lines ofthe television system. The output picture element data of the scanningline number converting circuit 121 is supplied to a memory 128 or 129through a switching circuit 122.

The digital video signal successively obtained time-sequentially fromthe decoder 119 with the signal format shown in FIG. 4, is supplied to asynchronizing signal detecting circuit 123, a header signal detectingcircuit 125, and a memory write controller 126. The synchronizing signaldetecting circuit 123 detects the synchronizing signal 54a or 54b andthe EOD signal within the header signal shown in FIG. 5, and supplies adetection signal to a control circuit 124. This synchronizing signaldetecting circuit 123 is constructed so that when the synchronizingsignal 54a or 54b is detected, the data of the five words (or elevenwords) obtained immediately after the detected synchronizing signal isnot detected as a synchronizing signal even if the value is the same asthat of the synchronizing signal 54a or 54b. Accordingly, it is possibleto prevent signals other than the synchronizing signals 54a and 54bwithin the header signal, and further, the picture element data, frombeing erroneously detected as the synchronizing signal. The headersignal detecting circuit 125 discriminates each of the codes within theheader signal shown in FIG. 5, and supplies a resulting output to thecontrol circuit 124.

The control circuit 124 is supplied with signals such as a synchronizingsignal detection signal from the synchronizing signal detecting circuit123, detection signals of each of the codes within the header signalobtained from the header signal detecting circuit 125, and a signal(category number signal) specifying the desired category (various kindsof special picture identified by the picture category identificationcode "P.G") selected by the user of the reproducing apparatus andapplied to an input terminal 127 by manipulating an external switch andthe like. The control circuit 124 discriminates each of the signalssupplied thereto, and controls the scanning line number convertingcircuit 121, the switching circuit 122, the memory write controller 126,a switching circuit 131, and the like. The output digital video signalof the scanning line number converting circuit 121 which is selectivelyproduced through the switching circuit 122, is supplied to one of thememories 128 and 129. The digital video signal supplied to one of thememories 128 and 129 is successively written in according to a write-incontrol signal from the memory write controller 126, at the addressesspecified by two of the address signals 56a through 59a (or 56b through59b) shown in FIG. 5. In the present embodiment, the reproducingapparatus reproduces the analog color video signal of the 525-linesystem, and for this reason, the output digital video signal of thescanning line number converting circuit 121 which is selectivelyproduced through the switching circuit 122 is successively written in atthe addresses after the conversion of the number of scanning linesspecified by the address signals 58a and 59a (or 58b and 59b). Inaddition, the header signals H₁ through H₂₈₆ and the EOD signal shown inFIG. 4 are not written into the memories 128 and 129, and the memorywrite controller 126 is controlled so that the video signal parts V₁through V₂₈₆ are written into the memories 128 and 129.

The memories 128 and 129 normally write in the reproduced pictureelement data alternately in terms of one frame or one field. However, inthe present embodiment, the memory 128 or 129 which is specified by thewrite-in specifying code "B19W" shown in FIG. 5 writes in the reproducedpicture element data within the horizontal blanking period.

The memories 128 and 129 simultaneously reads out the reproduced pictureelement data which is written in according to a read-out control signalfrom a memory read controller and synchronizing signal generator 130,and also compensate for the jitter introduced upon reproduction. Thedigital luminance signal read out from the memories 128 and 129 is readout with a sampling frequency of 9 MHz and a quantization number ofeight bits with respect to one picture, and the first and second digitalcolor difference signals read out from the memories 128 and 129 are readout with a sampling frequency of 2.25 MHz and a quantization number ofeight bits with respect to one picture. The digital luminance signal andthe first and second digital color difference signals thus read out fromthe memories 128 and 129, are supplied to the switching circuit 131.

The switching circuit 131 selectively produces the read out outputs fromone of the memories 128 and 129 according to a switching control signalfrom the control circuit 124, and supplies the selectively producedoutputs to digital-to-analog (D/A) converters 132, 133, and 134. Whenthe switching control signal from the control circuit 124 is theread-out specifying code "B19R" shown in FIG. 5, the switching circuit131 selectively produces the read out outputs of the memory 128 or 129which is specified by the read-out specifying code "B19R". On the otherhand, when the switching control signal from the control circuit 124 isa control signal obtained when the EOD signal is detected, the switchingcircuit 131 switches to selectively produce the read out outputs of thememory 128 or 129, which were not produced up to that point in time.

The time required for the switching circuit 131 to switch is normallyexceedingly short. However, when a special effect such as fade-in is tobe carried out, the switching circuit 131 is intentionally switchedgradually by taking a specific time period (one second, for example).

Among the three kinds of digital signals passed through the switchingcircuit 131, the digital luminance signal is converted into an analogluminance signal by being subjected to digital-to-analog conversion atthe D/A converter 132 and then supplied to an encoder 135. On the otherhand, the two kinds of digital color difference signals are respectivelyconverted into color difference signals (B-Y) and (R-Y) by beingsubjected to digital-to-analog conversion at the D/A converters 133 and134, and then also supplied to the encoder 135. The encoder 135 producesa color video signal in accordance with the NTSC system, from the threekinds of analog signals from the D/A converters 132 through 134 and thehorizontal synchronizing signal, vertical synchronizing signal, colorburst signal, and the like from the memory read controller andsynchronizing signal generator 130. This NTSC system color video signalthus produced from the encoder 135 is obtained through the outputterminal 136. This NTSC system color video signal is reproduced anddisplayed as a color still picture or a partially moving picture of highquality by a television receiver (not shown), and is used assupplementary information to the listener when the audio signals arereproduced as sounds through the output terminals 120a, 120b, and 120c.

In the reproducing apparatus described heretofore, the header signal isreproduced with a predetermined period. Hence, the picture transmissionidentification code "A/P" which is reproduced in continuous with thesynchronizing signal 54a is detected at the header signal detectingcircuit 125, to determine whether the type of transmission istransmission of the full picture or transmission of a part of thepicture. When it is determined that the type of transmission is thetransmission of the full picture, the number of words in one videosignal part is discriminated by a counter within the memory writecontroller 126. In a case where the synchronizing signal 54a is missingdue to dropout and the like, the synchronizing signal detecting circuit123 produces a synchronizing signal detection signal as if thesynchronizing signal 54a was reproduced with a predetermined period.Accordingly, the memory 128 or 129 can correctly carry out write-in ofthe picture element data according to the write-in control signal fromthe memory write controller 126.

When the various codes in the second word of the header signal aremissing due to dropout and the like, a flag signal will indicate such amissing state. The control circuit 124 is constructed to operate as ifthe codes within the header signal obtained immediately prior to theheader signal comprising the dropout and the like in its second word isobtained, according to this flag signal. Further, even when one of theaddress signals 56a through 59a are missing, a flag signal will indicatesuch a missing state. In this state, the memory write controller 126increments the addresses by one according to the flag signal, so thatthe subsequent incoming picture element data are written into the memory128 or 129 at addresses where the picture element data should originallybe written in. Because the addresses are incremented by one for everysix words constituting the picture element data of one line, the lastaddress of one video signal part comprising 684 words will becomesincremented by 114 from its original last address.

Therefore, even if there is dropout and the like within a part of theheader signal or within the entire header signal, it is possible tocompensate for such dropout and the like in the header signal.

Next, detailed description will be given with respect to theconstitution and operation of the memories 128 and 129, by referring toFIG. 15. In FIG. 15, M₁₁, M₂₁, . . . M₆₁, M₁₂, M₂₂, . . . , M₆₂, M₁₃,M₂₃, . . . , M₆₃, M₁₆, . . . , M₆₆ respectively are 64k-RAMs. Thesethirty-six 64k-RAMs are respectively supplied with an address signalfrom a common address signal generator 142 within the memory writecontroller 126. If the memories 128 and 129 are frame memories, it isnecessary to provide two sets of arrangements of thirty-six 64k-RAMseach comprising the RAMs M₁₁ through M₆₆, however, it is only necessaryto provide one set of the arrangement of thirty-six 64k-RAMs if thememories 128 and 129 are field memories. That is, if the memories 128and 129 are field memories, the memory part shown in FIG. 15 correspondsto the memories 128 and 129, a part of the memory write controller 126which is shown as the address signal generator 142, and a part of thescanning line number converting circuit 121 which corresponds to thesupplementary memory used for carrying out operations upon conversion ofthe number of scanning lines. On the other hand, if the memories 128 and129 are frame memories, the memory part shown in FIG. 15 corresponds toone of the memories 128 and 129, a part of the memory write controller126 which is shown as the address signal generator 142, and a part ofthe scanning line number converting circuit 121 which corresponds to thesupplementary memory used for carrying out operations upon conversion ofthe number of scanning lines. Although omitted in FIG. 15, the memorypart actually includes first and second buffer memories. The firstbuffer memory is provided for storing the picture element data groupscorresponding to 1H which are obtained through the switching circuit 122and transmitted by the upper eight bits of each of the words within thevideo signal part having the signal format shown in FIG. 4. The secondbuffer memory is provided for storing the picture element data groupscorresponding to 1H which are obtained through the switching circuit 122and transmitted by the lower eight bits of each of the words within thevideo signal part having the signal format shown in FIG. 4.

Each of the bits of the picture element data obtained from the first andsecond buffer memories are respectively supplied to switches S₁ throughS₆ having six contacts, through respective input terminals 143-1 through143-6. The switches S₁ through S₆ actually are analog switches whichoperate electrically. The switch S₁ supplies the MSB of the pictureelement data to one of the RAMs M₁₁, M₁₂, . . . , M₁₆. Similarly, aswitch S_(i) (i is an integer from 2 to 6) supplies the i-th bit of thepicture element data counted from the MSB (MSB is considered as thefirst bit) to one of the RAMs M_(ij) (j is an integer from 1 to 6).Accordingly, in the memory part shown in FIG. 15, the lower two bitsamong the eight bits of picture element data are discarded, however,there is substantially no effect on the reproduced picture by suchdiscarding of the lower two bits of the picture element data. It is ofcourse possible to add twelve more 64k-RAMs to the memory part shown inFIG. 15, to store all the eight bits of the picture element data.However, in the digital video signal reproducing apparatus for home use,it will be more advantageous to use the memory part having theconstruction shown in FIG. 15 in order to keep the cost of thereproducing apparatus low.

Next, description will be given with respect to the operation of thememory part shown in FIG. 15. For convenience' sake, description will begiven with respect to a reproducing apparatus in which the reproduceddigital video signal is directly supplied to the memories 128 and 129,and carries out reproduction to produce an analog color video signal inaccordance with the PAL system or the SECAM system. First, a 16-bitaddress signal having a value "0000" in hexadecimal is supplied to theRAMs M₁₁ through M₆₆ from the address signal generator 142. On the otherhand, the upper six bits of the picture element data Y₀ shown in FIG. 6are supplied to the RAMs M₁₁, M₂₁, M₃₁, M₄₁, M₅₁, and M₆₁ from the firstbuffer memory, through the switches S₁ through S₆. Hence, the MSB of thedata Y₀ is stored at the address "0000" in the RAM M₁₁, and the secondbit of the data Y₀ is stored at the address "0000" in the RAM M₂₁.Similarly, the third, fourth, fifth, and sixth bits of the data Y₀ arerespectively stored at the address "0000" in the respective RAMs M₃₁,M₄₁, M₅₁, and M₆₁.

Then, the value of the address is kept the same, and the switches S₁through S₆ are switched to respectively become connected to anothercontact. Thus, the upper six bits of the picture element data Y₁ arerespectively stored at the address "0000" in the respective RAMs M₁₂,M₂₂, M₃₂, M₄₂, M₅₂, and M₆₂. Similarly thereafter, the value of theaddress is kept the same to "0000" and the switches S₁ through S₆ aresuccessively switched to become connected to other contacts, and thefirst six bits of the picture element data Y₂, Y₃, (R-Y)₀, and (B-Y)₀are respectively stored at the address "0000" of the respective RAMs M₁₃through M₆₃, M₁₄ through M₆₄, M₁₅ through M₆₅, and M₁₆ through M₆₆. Bythese series of operations, the first divided picture element data groupin the first scanning line, that is, the four luminance picture elementdata and the two color difference picture element data, are stored intothe memory part. Next, an address signal having a value "0001" inhexadecimal is produced from the address signal generator 142, and theupper six bits of the picture element data Y₄, Y₅, Y₆, Y₇, (R-Y)₁, and(B-Y)₁ are respectively stored at the address "0001" of the respectiveRAMs M₁₁ through M₆₆. These operations are repeated by incrementing thevalue of the address by one, to complete storing of the picture elementdata groups in the first scanning line into the RAMs M₁₁ through M₆₆.Next, an address signal having a value "0072" in hexadecimal isgenerated by the address signal generator 142, and the upper six bits ofthe picture element data Y₄₅₆ of the first sampling point in the secondscanning line shown in FIG. 6 are respectively supplied to the RAMs M₁₁,M₂₁, M₃₁, M₄₁, M₅₁, and M₆₁ from the second buffer memory, through theswitches S₁ through S₆, and stored into these RAMs. Then, the value ofthe address is kept the same and the switches S₁ through S₆ areswitched, and the upper six bits of the picture element data Y₄₅₇obtained from the second buffer memory are respectively supplied to theRAMs M₁₂, M₂₂, . . . , and M₆₂. Accordingly, the MSB of the pictureelement data Y₄₅₇ is stored at the address "0072" in the RAM M₁₂.Similarly, the second, third, fourth, fifth, and sixth bits of thepicture element data Y₄₅₇ are respectively stored at the address "0072"in the RAMs M₂₂, M₃₂, . . . , and M₆₂. Thereafter, the value of theaddress is successively incremented by one to complete storing of thepicture element data groups in the second scanning line. The videosignal parts V₃, V₄, V₅, . . . are stored similarly, and the storing ofdata corresponding to one frame (or one field) is completed when thelast picture element data group in the 571-st and 572-nd scanning lines(or 285-th and 286-th scanning lines in the case of storing of datacorresponding to one field) are stored at the addresses "FE45" and"FEB7" (addresses "7EE9" and "7F5B" in the case of storing of datacorresponding to one field) in the RAMs.

Thus, the picture element data corresponding to one frame are storedinto the RAMs M₁₁ through M₆₆, or the picture element data correspondingto one field are stored into the RAMs M₁₁ through M₆₆ for two fields.Moreover, among the picture element data transmitted by the sixcontinuous words, the picture element data (four picture element data ofthe digital luminance signal and two picture element data of the digitalcolor difference signals) related to the same scanning line are storedat the same address in the thirty-six RAMs M₁₁ through M₆₆. Because thememory part shown in FIG. 15 is driven by the same address signal, it isnecessary to time-divisionally carry out the write-in and read-out.Hence, by using the read-out control signal from the memory readcontroller and synchronizing signal generator 130, the read-out withrespect to the RAMs M₁₁ through M₆₆ is carried out within a videointerval (approximately 51 μsec) in which the picture information istransmitted within a 1H period (64 μsec), and the write-in with respectto the RAMs M₁₁ through M₆₆ is carried out within the horizontalblanking period (approximately 13 μsec). In addition, the read-out withrespect to the RAMs M₁₁ through M₆₆ is carried out so that the above sixpicture element data stored at the same address in the respective RAMsare read out simultaneously, and the value of the address is incrementedby one from the value "0000".

When producing the analog video signal in accordance with the NTSCsystem from the reproduced signal, the number of scanning lines of thedigital video signal obtained from the decoder 119 is converted at thescanning line number converting circuit 121, before carrying out thewrite-in with respect to the memories 128 and 129. In this case, thewrite-in operations with respect to the memory part shown in FIG. 15 arethe same as those described heretofore, except in that the number ofdata is reduced to 5/6 the number of data in the above case due to theconversion of the number of scanning lines. Therefore, detaileddescription for this case will be omitted.

The music program and the color picture reproduced from the disc 70 mustbe reproduced in synchronism with each other. However, it takes apredetermined time period in order to store the picture element datacorresponding to one frame (or one field) into the memories 128 and 129,and the digital video signal must be recorded at a point which leads thepoint where the display of the picture is to be started by the abovepredetermined time period. Accordingly, the digital video signal whichis to be reproduced from the start of the music program, is recorded ata point which leads a point where the recording of that music program isstarted by the above predetermined time period. For this reason, when arandom access operation is carried out with respect to the disc 70, thereproducing stylus 110 is fed at a high speed from the outer peripheryto the inner periphery of the disc 70 to reproduce the control signalhaving the signal format shown in FIG. 11, and a chapter code within thereproduced control signal is compared with the chapter code of a desiredmusic program specified by the user. The reproduction of an arbitrarymode such as normal reproduction is started from a point where thereproducing stylus 110 has reached the beginning of the desired musicprogram, however, in such instances, the digital video signal may bereproduced from an intermediate point thereof, that is, not from thebeginning thereof. In such a case, if the synchronizing signal onlyexists at the beginning of the digital video signal corresponding to oneframe or one field of the picture, the digital video signal reproducedfrom the intermediate point thereof cannot be displayed. However,according to the present embodiment, the header signal is arrangedpreceding the divided picture element group corresponding to 2H as shownin FIG. 4. Hence, in the present embodiment, even if the digital videosignal is reproduced from the intermediate point thereof, it is possibleto write in and read out the digital video signal arranged subsequent tothe first header signal part which is reproduced beyond thatintermediate point and display that digital video signal.

In this case where the digital video signal is reproduced from theintermediate point thereof, when it is detected from the picturetransmission identification code "A/P" that the full picture istransmitted, it is possible to write in the picture element data intothe memory 128 or 129 until the EOD signal which is transmitted by thelast word of the digital video signal having the picture element datacorresponding to one picture is reproduced, and not display the digitalvideo signal reproduced from the intermediate point thereof until theEOD signal is reproduced. In this case, a part of the picture will bemissing in the display of the color still picture.

On the other hand, when it is detected that a part of the picture istransmitted, the digital video signal reproduced from the intermediatepoint thereof is normally not displayed. However, it is possible tocarry out successive display.

When displaying the lyrics of a song and the like at a part of thepicture, it is possible to quickly change the display of that part ofthe picture if the picture information related to that part of thepicture is transmitted in a concentrated manner. Similarly, it ispossible to display a moving picture within a limited part of thepicture. That is, when displaying a moving picture within a limitedsmall picture part 146 of a reproducing screen 144 shown in FIG. 16, anoperation is repeated in which the picture element data are transmittedin continuous with the header signal comprising the address signals 56athrough 59a and 56b through 59b which specify the addresses of thissmall picture part 146. The header signal is transmitted at a positionindicated by 145 in FIG. 16. However, this header signal is notdisplayed on the screen 144 as described before. The picture elementdata of the small picture part 146 are written into one of the memories128 and 129 from which the digital video signal corresponding to thepicture being displayed on the screen 144 is read out. As a result, thepicture element data of the small picture part 146 which is written intoone of the memories 128 and 129 are displayed within the small picturepart 146 as a moving picture. When transmitting a part of the picture,the transmission time differs according to the area of the display.Thus, a moving picture can be displayed if the transmission time of thepicture to be displayed within the small picture part 146 is short.

Description was given heretofore with respect to standard picturetransmission of the 625-line system. However, when carrying out picturetransmission of a system with the high definition or transmission of amoving picture according to the run-length code, the mode of the pictureis identified by the value of the picture mode identification code"MODE". Moreover, a picture transmission format different from thatshown in FIG. 6 is employed. In addition, the value of the picture modeidentification code "MODE" is identified to control the scanning linenumber converting circuit 121 and the memory write controller 126 by theoutput signals of the control circuit 124 according to the needs, andthe write-in and read-out formats of data with respect to the memories128 and 129 are selected. For example, when it is identified from thepicture mode identification code "MODE" that the digital video signal ofthe high definition system is reproduced, the memory write controller126 is controlled so that the memories 128 and 129 do not write in thereproduced high-definition digital video signal, or the memory writecontroller 126 is controlled so that the reproduced high-definitiondigital video signal is compressed and written into the memories 128 and129. Further, changes may be made in the operation of the scanning linenumber converting circuit 121 so that the number of scanning lines ofthe reproduced high-definition digital video signal is converted into625 lines or 525 lines from 1125 lines. Moreover, measures may be takenso that the transmission of data corresponding to one frame andtransmission of data corresponding to one field coexist. In this case,the number of words in the header signal is twelve (or six) and does notchange, however, the value of the picture information quantityidentification code "FR/FL" and the signal format of the digital videosignal are different. When transmitting data corresponding to one field,for example, the video signal parts which are divided in terms of 2H,and a total of 143 of such video signal parts are transmitted. Thereproducing apparatus identifies the above different value of thepicture information quantity identification code "FR/FL", and carriesout the write-in with respect to the memories 128 and 129 according tothe signal format of the digital video signal.

Moreover, even if the digital video signal supplied to the memories 128and 129 is shifted by one word due to some cause, such shift by one wordwill be corrected by reproducing the subsequent header signal, anderrors due to time-shift of words do not become accumulated.

Next, description will be given with respect to the recording andreproduction of the EOD signal. It will be assumed that the digitalaudio signal recorded on the disc 70 relates to a plurality of musicprograms, and that a recording interval A_(K) shown in FIG. 17(A)indicates the recording interval of the digital audio signalcorresponding to the k-th (k is an integer) music program while arecording interval A_(K+1) indicates the recording interval of thedigital audio signal corresponding to the (K+1)-th music program. If itis assumed that one color still picture among one or more pictures whichare successively reproduced during the reproducing interval of the(K+1)-th music program is displayed simultaneously as the start ofreproduction, the digital video signal related to this color stillpicture must be recorded as indicated by a digital video signalrecording interval B_(K+1) in FIG. 17(B). That is, the picture elementdata corresponding to one frame or one field and the header signal arerecorded in the digital video signal recording interval B_(K+1) at aposition prior to the start of the audio signal recording intervalA_(K+1). Moreover, the EOD signal at the last word of the digital videosignal corresponding to one frame or one field, is recorded at arecording interval E shown in FIG. 17(B) subsequent to the recordinginterval B_(K+1), at a position coinciding with the start of therecording interval A_(K+1). FIG. 17(B) shows a case where the digitalvideo signal relates to only one category of picture information.Another arrangement of the recording intervals is possible, where thepicture element data from the last row or last few rows (or last columnor last few columns) of the picture element groups are not recordedwithin the recording interval B_(K+1) shown in FIG. 17(B) and thesepicture element data are recorded immediately prior to the recordinginterval E of the EOD signal.

On the other hand, when digital video signals related to a plurality ofcategories are successively recorded, the digital video signal relatedto one of the categories must be reproduced simultaneously as the startof reproduction of the digital audio signal recording interval A_(K+1)shown in FIG. 17(A). FIG. 17(C) shows a case where there are digitalvideo signals related to two categories. The digital video signalsrelated to color still pictures of two categories are successivelyrecorded within recording intervals C_(K+1) and D_(K+1) in FIG. 17(C),without recording the EOD signal within these recording intervalsC_(K+1) and D_(K+1). A signal comprising the header signal having thesignal format shown in FIG. 5 and including codes "P.G" and the like forindicating the category of the picture recorded in the recordinginterval C_(K+1), and the EOD signal, is time-sequentially recordedwithin an interval E_(c) shown in FIG. 17(C). A signal comprising theheader signal having the signal format shown in FIG. 5 and includingcodes "P.G" and the like for indicating the category of the picturerecorded in the recording interval D_(K+1), and the EOD signal, istime-sequentially recorded within an interval E_(d) shown in FIG. 17(C),subsequent to the recording interval E_(c). The positions of theserecording intervals E_(c) and E_(d) of these signals are selected in thevicinity of the start of the recording interval A_(K+1) shown in FIG.17(A).

In the present invention, the digital video signal may be transmitted bythe transmission path of one or two channels among the four channels.Moreover, the transmission may be carried out in terms of frames orfields. Accordingly, the transmission time of the picture element datadiffers according to the transmission mode. When transmitting stillpicture, the recording must be carried out by taking into account thistransmission time of the picture element data corresponding to onepicture, so that the transmission of the picture element datacorresponding to one picture is completed before the point in time whenthe still picture is to be displayed on a display device. Thus, thestarting point of recording differs according to the above transmissionmode.

It is usually difficult to select the starting positions of recording inaccordance with the transmission mode to suitable positions in thedigital video signal recording system. Hence, picture element datacorresponding to substantially one picture may be recorded at a pointpreceding the point where the digital audio signal is to be reproduced,by a predetermined period, regardless of the transmission mode. Forexample, the picture element data of the picture element group in thelast row (or last column), which corresponds to the picture element datarequired to complete one picture with the above picture element datacorresponding to substantially one picture, and the EOD signal, or theEOD signal alone, may be recorded subsequent to the header signal with atiming matched with that of the picture display. In this case, itbecomes possible to specify the timing of the picture display in realtime, with respect to the digital audio signal which is recorded andreproduced simultaneously with the picture element data corresponding toone picture.

On the other hand, upon reproduction, the switching of the outputs ofthe memories 128 and 129 into which the picture element datacorresponding to one picture are written, is carried out at a point whenthe EOD signal is reproduced. Hence, the display timing of thereproduced picture can be selected according to the selection of therecording position of the EOD signal. In the examples shown inFIGS.17(A) through 17(C), it is possible to display the reproducedpicture almost simultaneously as the start of reproduction of the(K+1)-th music program. For example, the picture corresponding to thedigital video signal recorded within the recording interval D_(K+1)shown in FIG. 17(C) is displayed at the point when the EOD signalrecorded in the recording interval E_(d) is reproduced. In the caseshown in FIG. 17(C), if the picture corresponding to the digital videosignal recorded within the recording interval C_(K+1) is to bedisplayed, this picture will be reproduced prior to the start ofreproduction of the digital audio signal recording interval A_(K+1) by aperiod corresponding to the recording interval E_(d). However, thetransmission period of the recording interval E_(d) is exceedingly shortand is in the range of several tens of words, and for this reason, itwill be felt as if the display of the picture and reproduction of thedigital audio signal occurred simultaneously.

Synchronizing signal detection signals are periodically obtained fromthe synchronizing signal detecting circuit 123, and the synchronizingsignal detection signals are obtained with a period corresponding to 696words if the signal format shown in FIG. 4 is employed. However, asclearly seen from FIGS. 17(A) through 17(C), reproduction of thesynchronizing signal is interrupted after the picture element datacorresponding to substantialy one picture are reproduced. Accordingly,at this point in time, the control circuit 124 controls the memory writecontroller 126 so that the memories 128 and 129 do not carry outwrite-in operations. That is, the memories 128 and 129 are controlled soas to only carry out write-in of the video signal part reproducedsubsequent to the header signal.

All the sixteen bits of data reproduced from unrecorded intervalsbetween adjacent digital video signal recording intervals, where thedigital video signal is not recorded, are "0" as in the case of the EODsignal. However, the header signal is not recorded in these unrecordedintervals where the digital video signal is not recorded. Thus, the datareproduced from these unrecorded intervals will not be erroneouslydetected as the EOD signal, and the write-in operations of the memories128 and 129 will continue to be stopped by a control circuit and thelike. Accordingly, the switching circuit 131 is switched when the EODsignal is reproduced after the header signal is reproduced, so as toread out from the memory 128 or 129 into which the data was written upto that point. Strictly speaking, the switching circuit 131 is switchedwhen the code "B19R" within the header signal shown in FIG. 5 assumes avalve different from the value assumed up to that point and when the EODsignal is reproduced. If the EOD signal does not exist, the datareproduced subsequent to the header signal will become written into thememories 128 and 129 as the picture element data of the video signalpart.

Next, description will be given with respect to the operation in whichonly the picture information of a desired category is to be selectivelyreproduced, in a case where a plurality of picture information ofmutually different categories are recorded onto the disc 70. The userfirst selects a desired category number from various category numbersprinted on the label, accommodating case, and the like of the disc 70.Then, a picture category specifying signal corresponding to the theselected category number, is applied to the input terminal 127 in FIG.13. The control circuit 124 repeatedly carries out an operation in whichthis picture category specifying signal and the picture categoryidentification code "P.G" within the signal obtained from the headersignal detecting circuit 125 are compared, and the memory 128 (or 129)is controlled so as to write in the video signal part reproducedsubsequent to the reproduced header signal only when the comparedsignals coincide. Hence, only the picture information of the desiredcategory number is stored into the memory 128 (or 129), and read outfrom the memory 128 (or 129) to display the picture of the desiredcategory. Because such picture information is displayed in synchronismwith the music, the display is instantaneously switched to the displayof a subsequent picture information of the same category numbersimilarly stored in the memory 128 (or 129), when the reproduction ofmusic is continued for a certain time period. In this manner, it ispossible to continuously display the picture information of only thedesired category selected by the user, while reproducing digital audiosignal.

A selector (not shown) for applying the above picture categoryspecifying signal to the input terminal 127, is automatically set with acategory number having a first priority, when the power source isconnected to the digital signal reproducing apparatus. That is, in thecase where the digital video signal of the normal picture is reproducedfrom the fourth channel and the digital video signal in which pictureinformation of a plurality of mutually different categories aretime-sequentially multiplexed is successively reproduced from the thirdchannel as described before, and a volatile memory is used in the aboveselector, the selector is designed to be set automatically so that thepicture category specifying signal which specifies the digital videosignal in the fourth channel is obtained from the selector when thepower is turned on. By designing the selector in this manner, thepicture category specifying signal is prevented from assuming a randomvalue when the power is turned on, and moreover, it becomes possible toautomatically specify the picture category of the digital video signalin the fourth channel which is considered as being the category mostlikely to be specified. In addition, if a nonvolatile memory is used inthe selector, it is unnecessary to provide a circuit for automaticallysetting the category number of the first priority when the power isturned on.

Next, description will be given with respect to the recording andreproducing operations according to the present invention, when changingor switching the full picture in which a moving picture is displayed ata part thereof to a completely different color still picture. In FIG.18A, a color still picture X is displayed as background, and a movingpicture is displayed within a part thereof. If a part within the colorstill picture X is moved as indicated by an arrow in FIG. 18A in asequence W1→W2→W3→ . . . , this part within the picture X will appear onthe screen as if this part is moving, and the display of the partiallymoving picture is carried out. A case will now be considered where thefull display of such picture X having the moving picture display withina part thereof, is changed to the display of a completely differentcolor still picture Z shown in FIG. 18B.

Generally, the picture element data corresponding to one picture of thecolor still picture Z are transmitted in a continuous manner, aftertransmission of the picture element data corresponding to the abovepartially moving picture is completed. Hence, a method may be consideredaccording to which the movement in the displayed picture is stoppedduring transmission period of the picture element data corresponding toone picture of the color still picture Z, to change the display to thecolor still picture Z by detecting the EOD signal transmitted after theabove transmission period. However, according to this method, it is onlypossible to change the display to another color still picture after themovement in the displayed picture is stopped. Thus, this method posestoo much limitation from the artistic point of view and in making thevideo programs.

Accordingly, according to the present invention, the moving pictureinformation is transmitted in accordance with the movement in thedisplayed picture. Moreover, it is noted that intervals in whichtransmission does not take place are introduced as the speed of movementin the moving picture becomes slower. Hence, the picture element datacorresponding to one picture of the color still picture Z which is to bedisplayed subsequent to the display of the partially moving picture,according to the header signal at least comprising the synchronizingsignals 54a and 54b, the codes "B19W" and "B19R", and the addresssignals 56a through 59a and 56b through 59b, are divided and recordedonto the recording medium. Therefore, the above described problem iseliminated by reproducing the recording medium recorded in such amanner.

FIG. 19 diagrammatically shows the manner in which the recording iscarried out. In FIG. 19, picture element data x corresponding to onepicture of the color still picture X shown in FIG. 18A are recorded withthe signal format shown in FIG. 4. Then, a first digital video signalcomprising the picture element data corresponding to one picture of thecolor still picture Z which is to be displayed subsequent to the colorstill picture X and the header signal having the signal format shown inFIG. 5 are divided into n divided signals z₁, z₂, z₃, . . . z_(n). Thesedivided signals z₁ through z_(n) are recorded within unrecordedintervals other than recording intervals w₁, w₂, w₃, . . . w_(n) of asecond digital video signal which comprises the picture element data ofthe partially moving picture in which a part of the picture moves asindicated by W1, W2, W3, . . . in FIG. 18A and the header signal. Thatis, the divided signals z₁ through z_(n) are recorded within theunrecorded intervals in which the signals w₁ through w_(n) which arerecorded intermittently according to the movement in the partiallymoving picture do not exist. In FIG. 19, a signal comprising the headersignal and the EOD signal is recorded within a recording interval C, andthis recording interval C is arranged after the recording interval ofthe last divided signal z_(n) among the divided signals constituting onepicture of the color still picture Z.

When reproducing the disc 70 which is recorded with the digital videosignals as shown in FIG. 19, the picture element data x of the digitalvideo signal corresponding to one picture of the color still picture Xare successively written into one of the memories 128 and 129 within thehorizontal blanking period For convenience' sake, it will be assumedthat the write-in is carried out with respect to the memory 128. Then,the read-out with respect to the memory 128 is carried out within thevideo period, to display the full color still picture X on the screen.Next, the divided signal z₁ related to the color still picture Z whichis obtained by reproducing the subsequent recording interval, is writteninto the other non-displaying memory 129 within the horizontal blankingperiod, while read-out is carried out with respect to the memory 128within the video period. Further, the picture element data within thedigital video signal obtained by reproducing the subsequent recordinginterval w₁, are written at specified addresses in the memory 128 andread out. By this read-out carried out with respect to the memory 128,although the full color still picture X is displayed up to that point, apart of the displayed picture is changed and a picture similar to thatdisplayed up to that point is displayed within the part indicated by W1within the displayed picture shown in FIG. 18A.

Similarly, the picture element data reproduced from the recordingintervals of the divided signals z₂, z₃, . . . z_(n-1), z_(n) arewritten into the non-displaying memory 129 according to the code "B19W"within the header signal. On the other hand, the picture element datareproduced from the recording intervals w₂, w₃, . . . , w_(n) arewritten at addresses specified by the address signals 56a through 59aand 56b through 59b in the memory 128, according to the code "B19W"within the header signal, and then read out from the memory 128according to the code "B19R" within the header signal. As a result, apart of the displayed picture moves as indicated by W1, W2, W3, . . . inFIG. 18A, and the partially moving picture is displayed. The movement ofa part or the displayed picture in FIG. 18A is continued until thepicture element data reproduced from the recording interval of thedivided signal z_(n) are written into the non-displaying memory 129 andthe picture element data amounting to one picture are finally writteninto the non-displaying memory 129. The data read out from thenon-displaying memory 129 are selectively produced through the switchingcircuit 131 when the EOD signal recorded within the last recordinginterval C is reproduced. Accordingly the display can be switched andchanged to the completely different color still picture display Z fromthe partially moving picture, without stopping the movement in thepartially moving picture.

The dividing unit of the digital video signal recorded onto the disc 70according to the present invention, is not limited to the dividing unitemployed in the embodiments described heretofore. The requirement hereis to determine the dividing unit so that the human eye cannot detectthat the color and luminance are being changed independently, when thedisplay is gradually changed to a picture while another picture is beingdisplayed. For example, the digital video signal may be divided intounits of picture element data corresponding to a number of scanninglines in the range of ten at the maximum, and the digital video signalcan be transmitted by adding the header signal to the divided units ofpicture element data.

In the embodiments described heretofore, description was given byassuming that each of the video signal parts (divided picture elementdata groups) relate to the picture element data of two mutually adjacentscanning lines as shown in FIG. 20A, that is, to two rows of pictureelement data groups arranged horizontally. However, each of the videosignal parts may relate to picture element data of the range of two toten mutually adjacent columns of picture element data groups arrangedvertically as shown in FIG. 20B.

FIG. 21 shows a signal format of the digital video signal for a casewhere the digital video signal is divided into two columns of pictureelement data groups arranged vertically. Because one word consists ofsixteen bits and each of the picture element data having thequantization number of eight bits are respectively arranged in the upperand lower eight bits of one word, two picture element data aretransmitted by one word. A total of 572 luminance picture element datagroups in the first vertical column at the left most part of the screenare indicated by Y_(V1), and each of the picture element data arearranged in sequence from the top of the screen to the bottom of thescreen. As shown in FIG. 22, The picture element data Y₀ at theuppermost part of the screen is arranged in the upper eight bits of thefirst word, and the picture element data Y₄₅₆ at the second uppermostpart of the screen is arranged in the lower eight bits of the firstword. Similarly, the picture element data Y₉₁₂ is arranged in the uppereight bits of the second word, the picture element data Y₁₃₆₈ isarranged in the lower eight bits of the second word, the picture elementdata Y₁₈₂₄ is arranged in the upper eight bits of the third word, . . ., and the picture element data Y₂₆₀₃₇₆ at the lowermost part of thescreen is arranged in the lower eight bits of the 286-th word. A totalof 572 luminance picture element data groups in the second column fromthe left end of the screen are indicated by Y_(V2), and a total of 572luminance picture element data groups in the third column from the leftend of the screen are indicated by Y_(V3). Similarly, a total of 572luminance picture element data groups in the i-th (i is an integer from1 to 456) column from the left end of the screen are indicated byY_(Vi). Each of the picture element data are arranged similarly as theabove picture element data group Y_(V1), and the picture element datacorresponding to one vertical column are transmitted by 286 words.

In addition, a total of 572 picture element data groups of the firstdigital color difference signal arranged in the j-th (j is an integerfrom 1 to 114) column from the left end of the screen are indicated by(R-Y)_(Vj), and a total of 572 picture element data groups of the seconddigital color difference signal arranged in the j-th column from theleft end of the screen are indicated by (B-Y)_(Vj). Each of the 572picture element data groups corresponding to one column are arranged ina sequence starting from the top to the bottom of the screen in theupper eight bits of the first word, lower eight bits of the first word,upper eight bits of the second word, lower eight bits of the secondword, upper eight bits of the third word, . . . , and lower eight bitsof the 286-th word, and the picture element data corresponding to onecolumn are transmitted by 286 words. A header signal having six bits,for example, is added to the beginning of each of the above dividedpicture element data groups.

Further, as shown in FIG. 21, the above component coded signal has asignal format in which the signal is time-sequentially transmitted interms of units, where one unit comprises a total of six picture elementdata groups, that is, four picture element groups Y_(V)(4j-3),Y_(V)(4j-2), Y_(V)(4j-1), and Y_(V)(4j) and the two kinds of digitalcolor difference signals (R-Y)_(Vj) and (B-Y)_(Vj).

Moreover, the digital video signal corresponding to one frame or onefield may be transmitted by the two channels Ch-3 and Ch-4 shown in FIG.10. In this case, the digital video signal is time-sequentiallyreproduced from the two channels and transmitted by one transmissionline.

The number of scanning lines of the digital video signal is 625 in theabove described embodiments so that the signal recording format of thedigital audio disc such as the disc 70 can be made common throughout theworld. By employing such a signal recording format, there will be nolack of information when reproducing the video signal as a video signalin accordance with the PAL system or the SECAM system. However, thedigital video signal having 525 scanning lines may be recorded onto thedisc 70 instead. In this case, the recording is carried out by selectingthe product of the number of sampling points of the luminance signal inone scanning line and the effective number of scanning lines, to a valueslightly smaller than 2¹⁸. The effective number of scanning lines in the525-line system is in the range of 483 (=525×0.92). Hence, if it isassumed that 483 lines are to be transmitted, the number of samplingpoints in one scanning lines is set to 540 because 2¹⁸ ÷483=542.7. Theallowable range of the horizontal blanking period of the 525-line systemis up to 18% of the period corresponding to 1H, and the samplingfrequency becomes as follows.

    15.734×540/(1-0.18)=10.3 (MHz)

On the other hand, as sampling frequencies obtained by simple ratioswith respect to the sampling frequency of 13.5 MHz described before, asampling frequency of 10.125 MHz can be obtained by multiplying 3/4 to13.5 MHz and a sampling frequency of 10.8 MHz can be obtained bymultiplying 4/5 to 13.5 MHz, for example. Hence, if the samplingfrequency is set to 10.125 MHz, the number of sampling points becomes10,125,000/15,734=643.5. The above 540 sampling points in one scanningline is 0.839 times the number 643.5, and is 16.1% smaller than 643.5.However, sufficient picture information can be recorded and reproduced,because 16.1% is within the allowable range of 18% with respect to thehorizontal blanking period of the 525-line system, that is, the NTSCsystem.

The disc applied with the recording system and reproducing apparatusaccording to the present invention, is not limited to the disc in theembodiments described heretofore. The disc may be an electrostaticcapacitance type disc formed with guide grooves, a disc from which therecorded signals are read by a light beam, and the like. Further, whenthe television receiver comprises input terminals for three primarycolor signals R, G, and B, a matrix circuit may be used instead of theencoder 135. In this case, the matrix circuit converts the luminancesignal Y and the color difference signals (B-Y) and (R-Y) into the threeprimary color signals R, G, and B and supplies these three primary colorsignals R, G, and B to the respective input terminals of the televisionreceiver. Hence, it is possible to obtain a still picture of anexceedingly high quality by such a television receiver. In addition, thecolor difference signals recorded on the disc 70 may of course be acombination of color difference signals (G-Y) and (R-Y) (or (B-Y)), Iand Q signals, or the three primary color signals.

Further, the present invention is not limited to these embodiments, butvarious variations and modifications may be made without departing fromthe scope of the present invention.

What is claimed is:
 1. A digital video signal recording systemcomprising:first producing means for independently subjecting aluminance signal and two kinds of color difference signals of a colorpicture information to be recorded to digital pulse modulation, toproduce a digital luminance signal and two kinds of digital colordifference signals; second producing means for dividing said digitalluminance signal and said two kinds of digital color difference signalsinto picture element data groups, in terms of specific number of rows orspecific number of columns which are adjacent on a screen, and adding aheader signal at least comprising a synchronizing signal, a picture modeidentification code, and a picture information quantity identificationcode to a beginning position of each of said divided picture elementgroups comprising said digital luminance signal and said two kinds ofdigital color difference signals, to produce a digital video signalhaving a signal format in which said digital luminance signal, said twokinds of digital color difference signals, and said header signal aretime-sequentially multiplexed; and recording means for recording saiddigital video signal onto a recording medium.
 2. A digital video signalrecording system as claimed in claim 1 in which said first producingmeans comprises first digital pulse modulation means for subjecting theluminance signal to digital pulse modulation at a first samplingfrequency such that a product of a number of picture elements in onescanning line of said digital luminance signal and an effective numberof scanning lines in one picture of a standard television system isexceedingly close to 2¹⁸ but less than 2¹⁸, and second digital pulsemodulation means for independently subjecting the two kinds of colordifference signals to digital pulse modulation at a second samplingfrequency which is 1/N said first sampling frequency, where N is aninteger greater than or equal to two.
 3. A digital video signalrecording system as claimed in claim 2 in which said standard televisionsystem is a television system employing 625 scanning lines.
 4. A digitalvideo signal recording system as claimed in claim 3 in which said numberof picture elements in one scanning line is 456, and said effectivenumber of scanning line is
 572. 5. A digital video signal recordingsystem as claimed in claim 2 in which said second producing meansproduces said picture element data groups which are successivelytransmitted in terms of a unit, where said unit comprises a total of sixpicture element data constituted by four picture element data of saiddigital luminance signal and one picture element each of said two kindsof digital color difference signals.
 6. A digital video signal recordingsystem as claimed in claim 1 in which said second producing meansproduces said digital video signal with a signal format such that saidheader signal further comprises a picture category identification codefor identifying one category of picture information from among aplurality of mutually different categories of picture information.
 7. Adigital video signal reproducing apparatus for reproducing signals froma recording medium recorded according to the digital video signalrecording system claimed in claim 6, said reproducing apparatuscomprising:reproducing means for reproducing recorded signals from saidrecording medium on which said digital video signal is recorded; headersignal reproducing circuit for discriminating said header signal withinthe digital video signal reproduced by said reproducing means, andreproducing said header signal; two memory circuits into which saiddigital luminance signal and said two kinds of digital color differencesignals within said reproduced digital video signal are written, andfrom which said digital luminance signal and said two kinds of colordifference signals are simultaneously read out; memory control means fordetermining whether a value of said picture category identification codedetected by said header signal reproducing circuit coincides with anexternal picture category specifying signal specifying a desiredcategory, to write said divided picture element data groups reproducedin continuous with said header signal comprising said picture categoryidentification code having the value which coincides with said picturecategory specifying signal into one of said memory circuits, and readingout stored data from said one memory circuit; a digital-to-analogconverting circuit for subjecting said digital luminance signal and saidtwo kinds of color difference signals from said memory circuits todigital-to-analog conversion, and obtaining the luminance signal and thetwo kinds of color difference signals; and a circuit supplied withoutput signals of said digital-to-analog converting circuit, forproducing an analog video signal in accordance with a standardtelevision system.
 8. A digital video signal recording system as claimedin claim 1 in which said second producing means comprises means forgenerating a read-out instruction code and a signal transmissiontermination signal with a timing matched with a picture display of saiddigital video signal, in continuous with the digital video signalcomprising the picture element data groups corresponding to one picture,and adding said read-out instruction code and said signal transmissiontermination signal to said digital video signal.
 9. A digital videosignal reproducing apparatus for reproducing signals from a recordingmedium recorded according to the digital video signal recording systemclaimed in claim 8, said reproducing apparatus comprising:reproducingmeans for reproducing recorded signals from said recording medium onwhich said digital video signal is recorded; header signal reproducingcircuit for discriminating said header signal within the digital videosignal reproduced by said reproducing means, and reproducing said headersignal; two memory circuits into which said digital luminance signal andsaid two kinds of digital color difference signals within saidreproduced digital video signal are written, and from which said digitalluminance signal and said two kinds of color difference signals aresimultaneously read out; memory control means for reading out data fromone of said memory circuits which is written in with said pictureelement data corresponding to one picture, when said read-out specifyingcode detected by said header signal reproducing circuit is reproduced;switching means for switching with a timing in accordance with areproduced point of said signal transmission termination signal, toselectively read out from one of said memory circuits in which saiddigital video signal added with said signal transmission terminationsignal is stored, and produce said digital video signal added with saidsignal transmission termination signal; a digital-to-analog convertingcircuit for subjecting said digital luminance signal and said two kindsof color difference signals from said switching means todigital-to-analog conversion, and obtaining the luminance signal and thetwo kinds of color difference signals; and a circuit supplied withoutput signals of said digital-to-analog converting circuit, forproducing an analog video signal in accordance with a standardtelevision system.
 10. A digital video signal reproducing apparatus asclaimed in claim 9 in which said memory control means interrupt write-inof said header signal or said signal transmission termination signalupon reproduction of said header signal or said signal transmissiontermination signal.
 11. A digital video signal recording system asclaimed in claim 1 in which said second producing means produces saiddigital video signal with a signal format such that said header signalfurther comprises a write-in specifying code for specifying which memorycircuit within a reproducing apparatus, between a displaying memorycircuit reading out picture element data which are being displayed and anon-displaying memory circuit writing in picture element data which arenot being displayed, is to be written in with said divided pictureelement data groups.
 12. A digital video signal recording system asclaimed in claim 11 in which said second producing means comprises meansfor producing a first digital video signal comprising picture elementdata groups corresponding to one picture and a second digital videosignal comprising picture element data groups corresponding to a part ofone picture so as to display a moving picture in a part of a displayedpicture, intermittently transmitting said second digital video signal,and dividing said first digital video signal and transmitting saiddivided first digital video signal within unused transmission intervalsexcluding transmission intervals of said second digital video signal.13. A digital video signal reproducing apparatus for reproducing signalsfrom a recording medium recorded according to the digital video signalrecording system claimed in claim 8, said reproducing apparatuscomprising:reproducing means for reproducing recorded signals from saidrecording medium on which said digital video signal is recorded; headersignal reproducing circuit for discriminating said header signal withinthe digital video signal reproduced by said reproducing means, andreproducing said header signal; displaying and non-displaying memorycircuits into which said digital luminance signal and said two kinds ofdigital color difference signals within said reproduced digital videosignal are written, and from which said digital luminance signal andsaid two kinds of color difference signals are simultaneously read out;memory control means for writing said divided picture element datagroups reproduced in continuous with the header signal comprising saidwrite-in specifying code into said displaying memory circuit or saidnon-displaying memory circuit according to a value of said write-inspecifying code detected by said header signal reproducing circuit, andreading out picture element data from said displaying memory circuit; adigital-to-analog converting circuit for subjecting said digitalluminance signal and said two kinds of color difference signals fromsaid displaying memory circuit to digital-to-analog conversion, andobtaining the luminance signal and the two kinds of color differencesignals; and a circuit supplied with output signals of saiddigital-to-analog converting circuit, for producing an analog videosignal in accordance with a standard television system.
 14. A digitalvideo signal recording system as claimed in claim 1 in which said secondproducing means produces said digital video signal with a signal formatsuch that said header signal further comprises a picture transmissionidentification code for identifying whether said digital luminancesignal and said two kinds of color difference signals comprise pictureelement data groups corresponding to one picture.
 15. A digital videosignal reproducing apparatus for reproducing signals from a recordingmedium recorded according to the digital video signal recording systemclaimed in claim 14, said reproducing apparatus comprising:reproducingmeans for reproducing recorded signals from said recording medium onwhich said digital video signal is recorded; header signal reproducingcircuit for discriminating said header signal within the digital videosignal reproduced by said reproducing means, and reproducing said headersignal; two memory circuits into which said digital luminance signal andsaid two kinds of digital color difference signals within saidreproduced digital video signal are written, and from which said digitalluminance signal and said two kinds of color difference signals aresimultaneously read out; means for producing a synchronizing signaldetection signal even when said synchronizing signal is not detected,with a period with which the synchronizing signal detection signalshould originally be produced, when said header signal reproducingcircuit detects that said picture transmission identification codeidentifies the transmission as being a transmission of picture elementdata groups corresponding to one picture; memory control means forwriting said divided picture element data groups reproduced incontinuous with said synchronizing signal detection signal into one ofsaid memory circuits according to said synchronizing signal detectionsignal, and reading out the written in picture element data from saidone displaying memory circuit; a digital-to-analog converting circuitfor subjecting said digital luminance signal and said two kinds of colordifference signals from said memory circuits to digital-to-analogconversion, and obtaining the luminance signal and the two kinds ofcolor difference signals; and a circuit supplied with output signals ofsaid digital-to-analog converting circuit, for producing an analog videosignal in accordance with a standard television system.
 16. A digitalvideo signal reproducing apparatus as claimed in claim 15 in which saidmemory control means comprises means for writing said divided pictureelement data groups into one of said memory circuits when said picturetransmission code is not detected, according to a value of a picturetransmission identification code detected immediately prior to a pointwhen said picture transmission code is not detected.
 17. A digital videosignal recording system as claimed in claim 1 in which said secondproducing means produces said digital video signal with a signal formatsuch that said header signal further comprises address signals forindicating addresses in a memory circuit where said divided pictureelement data groups are to be written in.
 18. A digital video signalreproducing apparatus for reproducing signals from a recording mediumrecorded according to the digital video signal recording system claimedin claim 17, said reproducing apparatus comprising:reproducing means forreproducing recorded signals from said recording medium on which saiddigital video signal is recorded; header signal reproducing circuit fordiscriminating said header signal within the digital video signalreproduced by said reproducing means, and reproducing said headersignal; two memory circuits into which said digital luminance signal andsaid two kinds of digital color difference signals within saidreproduced digital video signal are written, and from which said digitalluminance signal and said two kinds of color difference signals aresimultaneously read out; memory control means for writing said dividedpicture element data groups reproduced in continuous with said addresssignals into one of said memory circuits according to values of saidaddress signals detected by said header signal reproducing circuit, andsuccessively reading out the written in picture element data from saidone displaying memory circuit; a digital-to-analog converting circuitfor subjecting said digital luminance signal and said two kinds of colordifference signals from said memory circuits to digital-to-analogconversion, and obtaining the luminance signal and the two kinds ofcolor difference signals; and a circuit supplied with output signals ofsaid digital-to-analog converting circuit, for producing an analog videosignal in accordance with a standard television system.
 19. A digitalvideo signal reproducing apparatus as claimed in claim 18 in which saidmemory control means writes a total of six picture element dataconstituted by four picture element data of said digital luminancesignal and one picture element each of said two kinds of digital colordifference signals being transmitted into one of said memory circuits atthe same address thereof.
 20. A digital video signal recording system asclaimed in claim 1 in which said header signal comprises same contentswhich are repeatedly recorded a plurality of times.
 21. A digital videosignal reproducing apparatus for reproducing signals from a recordingmedium recorded according to the digital video signal recording systemclaimed in claim 1, said reproducing apparatus comprising:reproducingmeans for reproducing recorded signals from said recording medium onwhich said digital video signal is recorded; header signal reproducingcircuit for discriminating said header signal within the digital videosignal reproduced by said reproducing means, and reproducing said headersignal; two memory circuits into which said digital luminance signal andsaid two kinds of digital color difference signals within saidreproduced digital video signal are written, and from which said digitalluminance signal and said two kinds of color difference signals aresimultaneously read out; memory control means for selecting a write-informat with which said digital luminance signal and said two kinds ofcolor difference signals are written into said memory circuits accordingto values of said picture mode identification code and said pictureinformation quantity identification code detected by said header signalreproducing circuit, to write in said digital luminance signal and saidtwo kinds of digital color difference signals into said memory circuitswith the selected write-in format, and reading out stored pictureelement data from one of said two memory circuits; a digital-to-analogconverting circuit for subjecting said digital luminance signal and saidtwo kinds of color difference signals from said memory circuits todigital-to-analog conversion, and obtaining the luminance signal and thetwo kinds of color difference signals; and a circuit supplied withoutput signals of said digital-to-analog converting circuit, forproducing an analog video signal in accordance with a standardtelevision system.
 22. A digital video signal reproducing apparatus asclaimed in claim 21 in which said header signal reproducing circuitstops the operation to detect the synchronizing signal immediately aftersaid synchronizing signal within said header signal is detected, withrespect to an input reproduced signal having a transmission intervalcorresponding to a specific number of words.